Combine tomatoes, onion, and cloves in a saucepan. Cook over medium heat 10 minutes or until onion is tender. Remove from heat; set aside.
Melt butter in a heavy saucepan over low heat; add flour, stirring until smooth. Cook 1 minute, stirring constantly. Add reserved tomato mixture; cook 2 minutes over medium heat, stirring occasionally. Strain mixture through a sieve; discard vegetables and spices. Serve sauce hot with veal cutlets or chops.