The light color sauce is a result of pink or golden beets. For darker sauce, use red beets.
Cut meat into 8 serving-size pieces. In a heavy, large saucepan or Dutch oven brown short ribs in hot oil over medium-high heat. Drain off excess fat. Add chicken broth, pepper, rosemary, thyme, and salt. Bring to boiling; reduce heat. Cover and simmer for 1 hour.
Meanwhile, clean fresh mushrooms. If using morel mushrooms, soak in a bowl of cold, lightly salted water for 15 minutes. Drain, rinse, and drain again. Wash other mushrooms by gently wiping with a damp towel or paper towel. Halve mushrooms.
For beets, remove roots and all but 1 inch of stems; wash beets well. Do not peel. Cut in half lengthwise.
For leeks, remove any tough outer leaves. Trim roots from base. Cut away tops leaving white portion. Slit lengthwise and wash well. Cut crosswise into 2-inch slices.
Add beets or carrots and lemon peel to meat mixture. Simmer, covered, for 20 minutes. Add mushrooms and leeks. Simmer, covered, 10 minutes more or until vegetables and meat are tender. Use a slotted spoon to transfer meat and vegetables to serving dish. Cover to keep warm.
Measure 1 cup cooking liquid. If necessary, add more chicken broth to make 1 cup. Return to large saucepan. In a small bowl stir together sour cream and flour. Stir into cooking liquid. Cook and stir until slightly thickened and bubbly; cook and stir for 1 minute more. Spoon meat and vegetables into serving bowls. Ladle sauce over meat and vegetables. Makes 8 servings.