Cut the pressed tofu into 1-inch cubes and place them in a large bowl.
In a separate bowl, whisk together the olive oil, soy sauce, lemon juice, cumin, smoked paprika, garlic powder, onion powder, salt, and black pepper.
Pour the marinade over the tofu cubes and toss gently to coat. Cover and refrigerate for at least 30 minutes, or up to 2 hours for more flavor.
While the tofu marinates, soak wooden skewers in water for about 30 minutes to prevent burning on the grill.
Preheat the grill or grill pan over medium-high heat.
After marinating, thread the tofu cubes, bell pepper pieces, zucchini rounds, and red onion wedges onto the skewers, alternating between the tofu and vegetables.
Place the skewers on the grill and cook for about 10-12 minutes, turning occasionally, until the tofu is golden and the vegetables are tender.
Remove from the grill and let cool slightly before serving.
Serve the kebabs warm, garnished with fresh herbs if desired.