Press the tofu for at least 30 minutes; squeeze out as much excess moisture as possible.
Mix all ingredients for the tofu marinade in a mixing bowl. This includes all the ground spices, garlic and ginger, lemon juice, salt, and yogurt. Add ~ 1-inch cubes of tofu to the marinade. Refrigerate for at least an hour, but the longer the better. Overnight marination will bring out the most flavor!
Soak wooden skewers in water for 30 minutes. If using metal skewers, no need to do anything.
Preheat the oven to 425 F.
Slice onion so that each piece has a few layers. Slice bell pepper into pieces that are easy to put on the skewer. Skewer on some tofu, onion, and bell pepper. Place on a baking sheet lined with parchment paper and bake for 30 minutes or until tofu is firm and crisp.