Cut the pumpkin and carrot into medium-sized pieces.
Cut the potato and apple into small pieces.
Finely chop the ginger, garlic and onion. Fry in a little oil in a casserole dish for 5 minutes over a low heat, stirring regularly.
Meanwhile, prepare a hot stock.
Add the pumpkin, carrots (and any other vegetables you wish to add to the recipe). Fry for 3 to 4 minutes, then cover the vegetables with the stock (up to 1 cm above the vegetables). If you run out of stock, you will need to make some more for the next step. Otherwise, set aside.
Immediately add the soy sauce and tomato sauce. Mix well and leave to cook for about ten minutes, stirring from time to time.
Then add the potato and apple.
Prepare the curry roux: in a small pan, melt the butter and add the flour. Stir constantly. Then add the spices once the butter and flour start to form a paste. Stir in a ladleful of stock (very gradually to get a pasty, not too liquid consistency - adjust the amount of stock needed to get the right consistency).
Add the roux to the pot with the vegetables. Mix well (if necessary with a whisk) to incorporate the roux.
Taste. If you like, you can add a little more spice. Then let the curry simmer on a low heat for about an hour, stirring occasionally.
The consistency of the curry will gradually thicken. After cooking, you can leave it to rest to obtain an even more pasty and creamy texture.