Pound chicken slightly to flatten into even thickness. Dredge lightly in flour, shaking off excess. Heat butter with oil in heavy large skillet over medium high heat. Add chicken (in batches if necessary) and saute on both sides until well browned. Add orange juice, wine, mushrooms, parsley, orange peel and rosemary and bring to simmer. Let simmer 5 minutes. Transfer chicken to heated serving platter using slotted spoon. Add vinegar to skillet and continue simmering, scraping up any browned bits, until sauce is reduced by 1/3. Pour sauce over chicken, garnish with orange sections and avocado slices. Serve immediately. Serve with a simple spinach salad, desert, bread, and a dry Chenin Blanc.