Pre-heat the oven to GM 4 / 350 °F / 180 °C. If using dried TVP mince, soak it in the vegetable stock until you're ready to use it. Boil the potatoes.
Chop and fry the onion. Add chopped leek and carrots. Add the stock and TVP mince, 1 tsp. mixed herbs, salt and pepper. Boil and simmer for a few minutes. Add the flour and peanut butter and cook for a few more minutes.
Mash the potatoes. Put the mixture in an ovenproof dish and top with the potato. Smooth the top with a fork.