Ricotta Dumplings in Tomato Onion Butter Marinara

Name: Ricotta Dumplings in Tomato Onion Butter Marinara
Ingredients: For the sauce; 1 28 ounce can whole peeled tomatoes; 1/2 stick of butter; 1 medium white or yellow onion, pelled & cut in half; salt and pepper to taste; 1/4 cup hot water; For the dumplings; 1/2 cup ricotta cheese (part skim is fine); 1/4 cup parmesan, asiago, or pecorrino; 1 egg white; 1 teaspoon lemon rind; 1/2 teaspoon salt; 1 teaspoon freshly ground pepper; 2/3 cup all purpose flour