• 1 small yellow onion, grated, or ½ cup minced green onion, including green tops
• 1 tablespoon olive oil (optional), plus oil for frying
• 1 pound cooked fish, flaked
• 1½ to 2 cups mashed potatoes
• 2 eggs
• 2 to 3 tablespoons chopped fresh flat-leaf parsley or dill (optional)
• Salt and freshly ground black pepper
• Matzoh meal or all-purpose flour
• Garlic mayonnaise or egg-and-lemon sauce (see fried fish)

If you think the raw onion will be too sharp tasting, warm the 1 tablespoon olive oil in a small frying pan and sauté the onion until barely softened, 3 to 5 minutes. Remove from the heat.

In a bowl, combine the fish, potatoes, onion, eggs, and the herb, if using. Mix well and season with salt and pepper. Form the mixture into 8 chubby cakes each about 3 inches in diameter. If the mixture does not hold together easily, fold in a little matzoh meal. (The croquettes can be formed up to 4 hours ahead of cooking, covered, and refrigerated.)

Pour olive oil to a depth of ¼ inch into a large sauté pan and place over medium heat. Spread matzoh meal or flour on a plate. Working in batches, dip the fish cakes in the matzoh meal or flour, coating evenly, and place in the hot oil. Fry, turning once, until golden on both sides and heated through, 4 to 6 minutes total.

Transfer to a platter and serve at once. Pass the sauce at the table.