2 tablespoons unsalted butter
1 large sweet onion, chopped (about 1 cup)
1 1/2 cups fresh or frozen beans (lima, edamame, fava, etc), cooked al dente
Kernels from 6 ears of corn (about 5 cups)
1 pint cherry or grape tomatoes, halved
1 tablespoon freshly squeezed lemon juice
1/4 cup feta cheese, crumbled
1/4 cup basil, sliced in chiffonade
Flaky sea salt and freshly ground black pepper, to taste