Making a Vinaigrette

The usual ratio is three parts oil to one part vinegar. Start with the acid in a bowl: vinegar or lemon juice, a pinch of salt, a teaspoon of mustard and a minced shallot if you like. Let the salt dissolve. Then whisk in the oil slowly so it emulsifies; the mustard helps it stay mixed. Taste it on a leaf of the salad, not off a spoon, and adjust. A jar with a lid works too: shake it hard for 20 seconds. Dress the salad right before serving so the leaves don't wilt.