Mix the yoghurt, garam masala and tomato purée together in a bowl. Add the tofu and turn until well coated. (If you have time, cover and leave to marinate in the fridge for up to an hour.)
Preheat the grill to high and oil a baking tray or grill pan. Thread the tikka cubes onto metal skewers, alternating with red and green pepper and red onion. Put the threaded skewers on the tray.
Brush the vegetables with the oil and grill for 3–5 minutes on each side, or until nicely charred and hot through. Be careful as the metal skewers may be hot.
Meanwhile, to make the dip, mix together the yoghurt and mint.
Serve the skewers with the yoghurt dip, salad and lemon wedges for squeezing over.
We loved it!