1) If using ears of corn, cut the kernels off and set aside. Discard the cobs.
2) Heat the oil in a large frying-pan over medium heat. Add the onions and cook, stirring occasionally, until softened, about two minutes. Add the garlic and cook for one minute more. Stir in the corn, butter beans, courgette, and tomatoes and cook, stirring occasionally, until the vegetables are tender, about seven minutes.
3) Spray a large non-stick frying or grill pan with cooking spray, and preheat it over medium-high heat.
4) In the meantime, prepare the scallops. Pat them dry and season them with 1/4 teaspoon of salt and 1/4 teaspoon of pepper. Add the scallops and cook until the inside is opaque, 5 to 6 minutes, turning once.
5) Stir the vinegar and basil into the succotash (vegetable mixture), season with additional salt and pepper to taste, and serve topped with grilled scallops. Garnish with parsley drizzle.
For the parsley drizzle:
Combine all ingredients in a blender and puree.