Stir-Fried Tofu with Bok Choy

Wrap the tofu in paper towels and drain in a strainer set over a bowl for 30 minutes. In a skillet, toast the sesame seeds over moderate heat until fragrant, 1 minute. Let cool, then grind to a coarse powder. In a large skillet, heat the sesame oil. Add the drained tofu, breaking it up into chunks with a spoon, and stir-fry over moderately high heat until lightly browned, about 3 minutes. Transfer the tofu to a plate. In the same skillet, heat the vegetable oil. Add the bok choy and stir-fry over moderately high heat until tender, 5 minutes. Add the bean sprouts and stir-fry until heated through. Stir in the tofu and season with the bouillon cube, salt and pepper. Transfer to a bowl and garnish with the sesame seeds.