Heirloom Tomatoes Stuffed with Summer Succotash

Preheat the oven to 425°. Bring a large saucepan of salted water to a boil. Add the lima beans and corn and boil until tender, about 3 minutes. Drain the beans and corn, transfer to a bowl and let cool. Slice off the bottom of each tomato so it sits flat. Using a knife, cut around the center of each tomato to form a cone that can easily be removed once the tomato is baked. Brush the tomatoes with olive oil and set them in a large pie plate, stem side up. Season the tomatoes with salt and pepper and roast just until tender, about 5 minutes. Let cool slightly, then spoon out and discard the centers to make room for the succotash. Meanwhile, in a large skillet, melt 1 1/2 teaspoons of the butter in the 1 tablespoon of olive oil. Add the bell pepper and cook over moderately high heat, stirring occasionally, until crisp-tender, about 3 minutes. Add the limas and corn and cook, stirring, for 2 minutes. Remove from the heat. Stir in the remaining 1 1/2 teaspoons of butter and the chives and season with salt and pepper. Spoon the succotash into the tomatoes and serve warm or at room temperature.