Serve this as an appetizer or snack, or as a meal with rice or noodles.
Cut tofu into 1/2-inch cubes, and put in a large bowl. Add peanuts to tofu, along with green onions.
Mash black beans with the flat side of a knife or pound with a mortar and pestle. Combine with peanut oil, sesame oil, and chile bean sauce in a small (1-quart) saucepan, and heat over medium heat until gently sizzling, about 2 minutes. Continue cooking, stirring constantly, until very fragrant, 45 seconds. Remove from heat, and stir in soy sauce and sugar.
Pour sauce over tofu, peanuts, and onions, and add chile oil to taste. With a spatula, distribute seasonings well. (You can make the tofu up to 2 hours ahead, then cover with plastic wrap.)