Pat tofu dry and cut into 1/2-inch cubes. Combine with 1/4 teaspoon five-spice powder in a medium bowl.

Heat canola oil in a large nonstick skillet over medium-high heat. Add tofu and cook, stirring every 1 to 2 minutes, until golden brown, 7 to 9 minutes total. Transfer to a plate.

Meanwhile, whisk water, oyster sauce, cornstarch and the remaining 1/4 teaspoon five-spice powder in a small bowl.

Add broccoli, yellow and red bell pepper to the pan and cook, stirring occasionally, until beginning to soften, about 4 minutes. Add ginger and garlic and cook, stirring, until fragrant, about 30 seconds. Reduce heat to low, add the oyster sauce mixture and cook, stirring, until thickened, about 30 seconds. Return the tofu to the pan along with peanuts and stir to coat with sauce; stir in hot sesame oil (if using).

Shopping tips: Five-spice powder is a blend of cinnamon, cloves, fennel seed, star anise and Szechuan peppercorns. Look for it in the spice section or with other Asian ingredients.

Be sure to use "oyster-flavored" sauce (it's oyster-free) to make this vegetarian; both it and oyster sauce are found in the Asian-food section or at Asian markets.

Ingredient note: Most supermarkets sell broccoli crowns, which are the tops of the bunches, with the stalks cut off. Although crowns are more expensive than entire bunches, they are convenient and there is considerably less waste.