Use any combination of fresh beans you like. They can be cooked ahead of time and refrigerated until you're ready to use them.
Trim stem ends of beans. Bring a large pot of salted water to a boil. Blanch each type of bean separately until crisp-tender. Refresh in ice water, drain, and pat dry.
Toss beans with shallot, oil, and salt and pepper to taste. Add vinegar to taste and herbs, if desired.
Arrange red-leaf lettuce and beans on each of 4 plates, and serve.