For a salad, you want beans that remain whole, plump, and firm. To get that, cook the legumes in plenty of salted water over low heat, checking them often; remove them from the heat before their skins start to split. Then drain and cool them quickly because beans left in their cooking liquid continue to cook. Add the dressing while the beans are warm; they absorb the oil and acid.
The goal for salad legumes is different from legumes for a stew. In a stew, you often want the beans to break down and thicken the sauce; in a salad, each bean should be visible on its own and remain whole when picked up with a fork. They also need to be fully cooked; leaving them firm is not a technique choice but undercooking. The desired point is between those two states, and you can find it only by checking often. That is why the cooking window for salad legumes is narrower than for legumes used in a stew. Cooking them for salad should therefore be planned as a short task that requires attention.
Cook them in plenty of water. In a narrow pot, the beans rub against each other and their skins come off; in a wide pot, they can move around freely. Salt the water because salt helps the skins soften evenly and seasons the beans inside. After the first boil, lower the heat and keep the water at a gentle simmer; a hard boil is the biggest enemy of salad legumes. If using dried beans, do not skip the initial full boil for 10 minutes here, either. Once that time is up, lower the heat and continue cooking at a gentle simmer.
Start checking early and repeat often. Take out and taste a few beans well before the recipe’s stated time; because they are not all the same size, try three or four each time. The beans have reached the right point when they mash without resisting your teeth but their skins are still on. If the skins have started floating in the water, it is too late; immediately remove the pot from the heat. Put the beans taken for tasting in a bowl and try them once they have cooled; a hot bean feels softer than it is.
Cooling is a critical step here. Legumes left in their hot cooking water continue to cook and pass the desired texture within 10 minutes. That is why you drain them and spread them in a single layer on a wide tray to cool quickly. An ice bath is another option, but it can split the skins; spreading them on a tray is safer and does the same job. If you turn the beans on the tray from time to time with a spatula, the ones underneath are exposed to the air too.
When you add the dressing determines the result. If you toss the legumes with olive oil, lemon, and salt while they are still warm, they absorb these flavors and stay tasty after cooling. Dressing added after they cool stays only on the surface. Add watery ingredients such as onion, parsley, and tomato close to serving; if added earlier, water collects at the bottom of the salad. If preparing the salad one day in advance, store the legumes with their dressing and the other ingredients in separate containers in the refrigerator; refrigerate the dressed legumes within 2 hours of cooking. Taste the salad once more before transferring it to the serving dish and refresh the lemon if needed.