Heat the vegetable oil in a large frying pan and fry the onion and garlic gently, stirring occasionally, for 4–5 minutes until softened.
Add the sweet potatoes and cook, stirring, for 2 minutes, then stir in the curry powder and ginger and cook for 30 seconds.
Stir in the tomatoes with their juice, and the stock. Bring to the boil, then reduce the heat, cover and cook gently for 12–15 minutes until the sweet potato is tender when pierced with a knife.
Stir in the peas and simmer for 3 minutes, then add the diced paneer or tofu and cook for a further 2 minutes until heated thoroughly. Season to taste, scatter with the chopped mint and serve hot.