Concasse: The Prepared Tomato That’s the Starting Point for Countless Sauces

“Concasse is one of those preparations that seems like extra work until you understand what it does. The skin adds nothing pleasant to a finished sauce; it curls, toughens, and creates an unpleasant texture. The seeds and their surrounding gel add water and bitterness. Remove both, and what remains is clean, concentrated tomato flesh that cooks down beautifully, integrates smoothly into sauces, and contributes nothing unwanted to the dish. The extra five minutes are worth it every time the tomato matters in the finished result.”

What Is Concasse

Concasse (pronounced kon-kah-SAY, from the French concasser, meaning “to crush” or “to pound”) is a classical French culinary preparation in which tomatoes are blanched to loosen the skin, peeled, halved, seeded, and then diced into a precise, clean cut. The result is a refined form of prepared tomato, free of skin and seeds, consisting only of the clean flesh, used as a component in sauces, soups, garnishes, and finished dishes where a pure, clean tomato element is required.

While the word concasse technically refers to any coarsely ground or crushed ingredient (pepper concasse, for instance, refers to coarsely cracked peppercorns), in virtually all culinary contexts it specifically means the tomato preparation described above. Tomato concasse is one of the most foundational vegetable preparations in classical French cooking and appears in a wide range of finished dishes, both as an integral ingredient and as a refined garnish.

Why Remove the Skin and Seeds?

This is the most common question about concasse, particularly from home cooks who are used to using whole tomatoes in cooking. The reasons are both textural and flavor-based.

• The Skin — Tomato skin doesn’t break down pleasantly during cooking. Instead, it curls, toughens, and detaches from the flesh, producing unpleasant curled pieces in a sauce or finished dish. In a rough home sauce, this may be acceptable or unnoticeable; in a refined preparation where texture and visual clarity matter, the skin is an unwanted element.
• The Seeds and Surrounding Gel — The seed cavities of a tomato are surrounded by a watery, slightly gelatinous liquid that is higher in water content than the flesh itself and that contains more of the tomato’s bitter compounds than the flesh does. In a sauce, this liquid adds unwanted water (diluting the sauce and extending the required reduction time) and some bitterness. Removing the seeds produces a cleaner, more concentrated tomato flavor in the finished preparation.
• What Remains — The cleaned tomato flesh that remains after blanching, peeling, and seeding is a cleaner, more concentrated ingredient that cooks down faster, produces a sauce with better texture, and contributes only the positive aspects of the tomato’s flavor without the diluting and slightly bitter elements of the seeds and the textural problem of the skin.

The Concasse Technique

• Step 1: Score the Tomatoes — Using a sharp paring knife, cut a shallow X on the bottom (flower end) of each tomato; just enough to break through the skin without cutting deeply into the flesh. This gives the blanching water a starting point to penetrate under the skin.
• Step 2: Blanch Briefly. — Lower the scored tomatoes into rapidly boiling water for 15–30 seconds; the exact time depends on the ripeness of the tomatoes (riper tomatoes need less time) and can be judged by watching the scored skin peel back at the X. Remove immediately.
• Step 3: Shock in Ice Water — Transfer directly to an ice bath to stop cooking immediately. The tomato should still be raw on the inside; only the skin has been affected by the brief blanch.
• Step 4: Peel — Starting from the X, the skin should peel away cleanly in strips. If it resists, return to the boiling water for a further 10 seconds. Fully ripe tomatoes peel with almost no resistance.
• Step 5: Core and Halve — Remove the core with a paring knife, then halve the tomato horizontally along its equator.
• Step 6: Remove Seeds — Using a finger or a small spoon, scoop or squeeze the seeds and their surrounding gel from each cavity. The goal is to remove the seeds cleanly without removing significant amounts of flesh.
• Step 7: Dice — Lay the halved, seeded tomato flat and dice the flesh to the required size. For a standard concasse, the dice are approximately 5–8mm (¼ inch), though some preparations call for a finer brunoise or a rougher chop.

Standard Applications of Tomato Concasse

• Sauce Base — The most fundamental use. Concasse cooked down in olive oil with garlic, and seasoning is the starting point for a clean, refined tomato sauce, which the French call a coulis de tomates.
• Beurre Blanc or Butter Sauce Component — A small amount of concasse adds color, acidity, and freshness to a butter sauce without the weight of a pureed tomato.
• Garnish for Consommé or Clear Soups — A few perfectly diced pieces of concasse floating in a consommé add color and a fresh tomato note without clouding the clear broth.
• Salsa and Fresh Preparations — Where a clean, seed-free, skin-free tomato element is needed for raw preparations.
• Pasta Sauces — Concasse cooked briefly in olive oil with garlic, fresh basil, and seasoning produces a quick, clean pasta sauce with a fresh tomato character distinct from a long-cooked, broken-down tomato sauce.
• As a Garnish — A small spoonful of fine concasse adds a vibrant color contrast and fresh flavor to plated meat, fish, or vegetable dishes.

Choosing the Right Tomatoes for Concasse

Concasse is only as good as the tomatoes used. Since the preparation removes the skin and seeds, which in lower-quality tomatoes may be the most prominent flavor components, what remains in an underripe or watery tomato is thin and disappointing.

Best Varieties

Plum tomatoes (Roma, San Marzano) are the most practical choice for concasse; they have thicker flesh, fewer seeds, and less water than round tomatoes, producing more flesh per tomato and a more concentrated flavor after peeling and seeding. Ripe heirloom tomatoes produce exceptional concasse when in season.

Ripeness Matters Most

The tomato should be fully ripe but still firm enough to dice cleanly. Over-ripe tomatoes produce a mushy concasse; under-ripe tomatoes lack flavor.

Frequently Asked Questions

Can You Use Canned Tomatoes to Make Concasse?

Good-quality whole canned tomatoes, San Marzano in particular, can be used to approximate concasse quickly: drain the liquid, remove the seeds by hand, and roughly chop or dice the flesh. The result lacks the same fresh, vibrant quality as properly made concasse from fresh tomatoes. Still, it is a practical and often excellent substitute outside of peak tomato season, when fresh tomatoes may be unavailable or flavorless.

What Is the Difference Between Concasse and Tomato Puree?

Tomato puree is cooked and often strained to a smooth consistency. Concasse is prepared raw, blanched only to loosen the skin, and diced into pieces, maintaining its texture. Concasse, which is then cooked down in a pan, produces a sauce; uncooked concasse is a raw, chunky, fresh preparation. The two are used in very different applications.

Is the Blanching Step Necessary?

For the cleanest result, yes. Some cooks skip blanching and attempt to peel tomatoes with a peeler or a sharp paring knife; this is possible for very ripe tomatoes but produces uneven results and often tears the flesh. The 20-second blanch is the most reliable way to produce consistently clean peeling with minimal flesh loss. If you have a very ripe tomato and a very sharp paring knife, the peel can sometimes be removed without blanching, but blanching remains the standard technique.

Key Terms Related to Concasse

• Blanching — The initial step in concasse preparation: the brief boil that loosens the tomato skin.
• Brunoise — A very fine concasse dice, used in refined garnish and sauce applications.
• Mise en Place — Concasse is always prepared as mise en place; it requires time and attention that cannot be given during active cooking.
• Reduction — Concasse cooked in a pan reduces more cleanly and quickly than a whole tomato because the water-heavy seeds have been removed.
• Mirepoix — Some classical preparations combine a fine mirepoix with concasse as the aromatic and vegetable base of a sauce.