Dice the potatoes and mix with the rest of the ingredients. Bake in the oven at 200 degrees top / bottom heat for about 35 - 40 minutes on the middle rack.
For the sauce, drain the chopped tomatoes in a sieve and puree them in a blender with the remaining sauce ingredients and a dash of water.
Dice the tofu and fry all over in a pan in oil. Remove and drain on kitchen paper.
Pour the sauce into the pan and bring to the boil for 5 minutes while stirring. Add the tofu cubes to the sauce and warm up for another 3 minutes.
Serve the potatoes and masala in separate bowls and sprinkle with chopped coriander.