To the mortar (deep bowl) add chopped basil, lime (cut in half and then each half cut again), onion powder, white pepper, cilantro, garlic, lemongrass, salt and olive oil.
Mash the ingredients together using a pestle.
Crumble tofu with the fork, then add to the mortar. Mash again, making sure all the ingredients mixed well together.
Heat the oil in a saucepan over medium heat. Add tofu mix and sauté for 4 or 5 minutes or until the tofu is light brown.
Towards the end add thinly sliced red onions. Cook them for a few moments, as you want to keep them crisp.
Once tofu is cooked, remove lime wedges. Place tofu in a medium bowl and combine with chopped mint and fresh lime juice.
Serve in the lettuce leaves.