Wash the vegetables, lettuce and basil and drain well. Cut the bell pepper into quarters, remove the stem and seeds and cut it into inch-wide strips. In a small saucepan boil the bell pepper strips in lightly salted water for about 5 minutes.

Cut the eggplant and zucchini into thick slices. Remove the mushrooms' stems. Slice the demi-baguettes in half and spread them with butter, setting 1 tablespoon of butter aside. Tear the lettuce leaves into large pieces and divide the lettuce and the basil evenly among the baguettes.

Place the vegetables along the edge of the grill (indirect heat) and leave them on for about 12-15 minutes, turning them over several times. The oyster mushrooms only need about 6-8 minutes on the grill.

On a large plate gently mix the grilled vegetables with specks of butter and salt and pepper to taste. Divide the vegetables evenly on the baguettes and serve.