In a large bowl, mix together the yogurt with all the ingredients, up to and including the mint.
Stir in the onion, peppers and tofu.
Cover the bowl and refrigerate for at least 4 hours.
After marinating, remove the bowl from the fridge. Take 4 large skewers or 8 small ones.
Preheat the oven to 450 degrees F.
Split up the tofu, onions and peppers to evenly place a mixture of each on all the skewers.
Line a baking tray with parchment paper. Place the skewers side by side.
Bake for 10 minutes, then turn the setting to broil for 3 minutes. The tofu should start to look charred.
Remove from the oven. Squeeze a lemon wedge over top, sprinkle some chaat masala and serve! (These skewers are best served with a green chutney).