- Prepare a hot grill or preheat broiler. Grill or broil onion slices, turning once, until lightly charred on both sides, about 3 to 4 minutes per side. Let cool, then cut into ¼-inch dice.
- In a large bowl, combine the charred onion, butterbeans or field peas, tomatoes, corn, shallot, dill, and chives.
- Stir in sherry vinegar and season with salt and pepper. Stir in olive oil, taste, and adjust seasoning as needed.