Peel (if need) and chop potatoes and add to a pan of boiling water - cook until tender and ready to be mashed.
Heat oil in a pan and add mince, garlic, onion and cumin and cook until mince is browned.
Add the tomatoes, mixed herbs and gravy and combine well. Add the chopped vegetables, reduce the heat and simmer for 10 minutes until sauce thickens and the vegetables are soft.
Preheat the grill to medium-high. Transfer the mince mixture to an ovenproof dish and top with the mashed potatoes. Place dish under the grill until the top is lightly browned. You can brush with milk or a sprinkle of cheese to help it brown.