Preheat oven to 450o F.
Wash the clams under cold running water, scrubbing them with a stiff brush. Lay in a single layer in 2 nine by twelve inch shallow baking dishes. Cover with the tomatoes, onions, garlic, jalapeno, pepper flakes, wine, water and butter.
Bake the clams for 6 to 7 minutes. Turn the clams and stir them to move those in the center to the sides of the pans. Bake for 10 to 15 minutes longer, or until the clams open. Discard any unopened clams.
Spoon the clams into shallow soup bowls. Using tongs, distribute the tomatoes and onions evenly among the bowls. Pour the broth into the bowls, sprinkle with the scallions, and garnish with the lemon wedges. Serve immediately.
Makes 6 servings.