In 5-quart Dutch oven or 10-inch straight-sided skillet, heat oil over medium heat to 375°F. Dip bell pepper and broccoli into batter; let excess batter drip back into bowl. Cook in single layer in hot oil 3 to 4 minutes, turning once, until coating is crisp and golden brown. Drain on paper towel-lined plate, then transfer to pan and place in oven to keep warm. Wait for oil to reach 375°F again between batches.