Depending on the berries’ texture, work them through a food mill with the finest insert or purée them in a food processor, and then work them through a chinois to obtain a coulis. Start with 2½ teaspoons (7 grams) powdered gelatin or 2 sheets gelatin, and 1 cup (250 milliliters) coulis. Bloom the gelatin (see Note). To preserve the bright flavor of uncooked fruit, heat only a small amount of the coulis (about four times the volume of the bloomed gelatin). Add the gelatin and let it dissolve. Stir the gelatin mixture into the rest of the cold coulis and stir thoroughly so the gelatin doesn’t clump up. Chill in the refrigerator for 30 minutes or more to set.