If using bacon, fry in a skillet until crisp. Remove bacon from pan, cool, and chop. Drain all but 1 tablespoon bacon fat from pan. (If not using bacon, add 1 tablespoon olive oil to pan.) Add pecans and onions. Sauté until pecans are toasted and onions are opaque, 6–8 minutes. Stir bacon, pecans, and onions into broccoli. Add cherries.