Heat oil in large nonstick skillet over medium heat. Add bell pepper and green onions; cook 5 minutes. Stir in vegetable stock, garlic, and saffron; bring to a boil. Sprinkle uncooked rice over ingredients, reduce heat to medium-low, and simmer, covered, 10 minutes.
Sprinkle broccoli, peas, tomatoes, and olives over rice. Cover, and cook paella for 8 minutes, or until rice is tender (if the rice hasn't cooked through, add more stock or water and simmer). Remove from heat, and let rest, covered, 5 minutes. Season with salt and pepper, if desired.
To serve, spoon paella into bowls, and garnish each with lemon wedges and parsley.