1. Cut chicken breasts into halves and lb with a mallet to 1/2-inch thickness.

2. Sauté chicken in a large skillet in margarine for 20 minutes. Set aside on a platter.

3. Stir flour into pan drippings, then add broth. Cook and stir until mixture thickens and bubbles. Add a few spoonfuls of this sauce to the yogurt in a small cup (to warm it), then add the yogurt to the sauce in the pan. Add the mustard and chicken and heat through for 10 minutes but do not boil, as boiling will cause the yogurt to separate.