Remove the tofu from the packaging, then drain any liquid and wrap in kitchen paper. Place on a small plate, then place another plate with a weight (such as a tin of beans) on top to remove excess moisture for at least 1 hour. Soak 8 skewers in water.
Once the tofu has finished draining, cut it into 32 even pieces. Combine the yogurt, turmeric, cumin, garam masala, chilli powder, garlic and ginger with some seasoning and stir well. Place the tofu in a bowl and coat with the yogurt mixture, being careful not to break the tofu up as you do so. Thread the tofu on to the skewers, alternating with the peppers and onion.
Brush a griddle pan with the vegetable oil and place over a medium/high heat. Add the skewers and cook for 4-5 minutes on each side, until there are golden griddle marks all over. Be careful when turning to make sure they don’t stick to the pan.
Meanwhile, mix together the yogurt, mint leaves, cucumber and cumin. Serve with the kebabs.