French Vegetable Soup

A thrift soup with no measurements at all — the method matters more than quantities. Two points decide whether it tastes like a purée or like dishwater: how far you brown the vegetables, and how little water you add.

• Choosing the vegetablesCooked leftovers work best if they are mild and starchy — carrot, potato, peas, green beans, celery, leek, turnip in moderation. Keep strong brassicas (cabbage, broccoli, brussels sprouts) to a small fraction or they will dominate the pot, and avoid beets unless you want a pink soup.
• Leftovers, and how oldVegetables already cooked and refrigerated should be no more than three or four days old and should smell clean. The soup is boiled again, so a brief simmer is fine, but nothing sour or slimy should go in on the theory that cooking will fix it.
• "Brown them all"This is the flavour of the dish. Use a wide pan over medium-high heat and enough fat to coat — roughly 2 tablespoons butter for 4 cups of chopped vegetables — and let them take real colour on the cut faces before any water goes in. Already-cooked vegetables are often wet, so give them room in the pan and let the surface moisture drive off before expecting colour.
• "Just enough water to cover"Take this literally. The cooking liquid becomes the soup, so extra water thins the finished purée and cannot be seasoned back. Stock in place of water is an improvement the original would not have objected to.
• Drain, sieve, recombineThe two-step drain-and-sieve most likely reflects hand-sieving: pulp is easier to push through a wire sieve when it is not swimming in liquid. A blender or stick blender does the whole job in the pot in under a minute; no draining needed. Pass it through a sieve afterwards only if fibrous vegetables leave threads.
• ConsistencyAim for something that coats a spoon lightly. If it is thin, simmer uncovered a few minutes; if it is heavy, loosen with hot stock or water so the soup stays at serving temperature.
• SeasoningThe paprika called for would have been a mild, sweet type, used as much for colour as for heat. Salt at the end as well as the beginning — cooked leftovers vary wildly in how much salt they already carry.
• The toast squaresSmall squares of bread toasted dry, cut about half an inch. Cube the bread first, then toast at 375F for 8–10 minutes, turning once, so the cubes crisp through instead of staying soft in the middle. Add them at the table; they collapse in the bowl within a minute or two.
• YieldAbout 4 cups of prepared vegetables plus their cooking water gives roughly four first-course servings.