Preheat oven to 450 degrees.
Make bread crumbs:
In a small bowl combine bread crumb ingredients. Bread crumbs may be made 1 day ahead and chilled, covered.
Lightly brush a shallow baking pan with additional oil and in it arrange tomatoes in one layer. Brush tomatoes with remaining tablespoon oil and season with salt and pepper. Wrap garlic tightly in foil and roast tomatoes and garlic in pan in middle of oven about 20 minutes, or until tomatoes are lightly browned and garlic is tender when pierced with a knife. Peel garlic and in a blender puree with tomatoes and vinegar until smooth, adding some water if coulis is too thick and season with salt and pepper. Coulis may be made 1 day ahead and chilled, covered.
In a saucepan heat coulis over low heat, thinning with more water if coulis too thick, and season with salt and pepper. Keep coulis warm.
In a small bowl stir together mayonnaise and mustard. Arrange fish fillets in a lightly oiled shallow baking pan and season with salt and pepper. Spread mayonnaise mixture evenly on top of fillets and pat bread crumbs evenly on top. Roast fillets in middle of oven until just cooked through, 7 to 10 minutes.
Serve fillets on top of coulis.