Slice fennel into 1/4-inch pieces, place in pot with 3 cups water and lemon. Simmer for 10 to 15 minutes until tender. Discard lemon, drain, and set aside. Saute chopped onion in 2 Tablespoons butter for 3 minutes. Add 1 pinch saffron and risotto and stir. Add water in 1/2 cup increments and stir constantly as water evaporates. Continue to add water and stir until risotto is cooked but still al dente.
Season sea bass with salt and pepper and place in pan with fennel, kalamata olives, orange zest, 2 Tablespoons butter, chicken stock or fish bouillon, and white wine in a braising pan. Cook at 400 degrees for 6 to 10 minutes until fish is tender but cooked through.
Divide risotto on 4 plates and place the fish on top. Place fennel and olive mixture around the fish and serve with some braising liquid.
Other Notes
White wine, a light salad and fresh baked-rolls make great companions to this dish.