15-16 clams, rinsed, sand and grit removed1 onion, minced1 stick butter1 tablespoon chopped fresh parsley2 garlic cloves, minced3 teaspoons lemon juice1 cup bread crumbs1 cup chopped chouriço sausage1 tablespoon clam juice (or cooking liquid from steaming the clams)1/4 cup grated Parmesan cheese1 lemon, sliced thinlySalt and pepper to taste