Cut the venison filet into thin strips. Finely chop the leek, dice the sweet potato, season with salt, pepper and thyme, and then sauté in a little olive oil. Add the venison and cook until tender. Butter a frying pan, place in a tortilla, grate over some cheese, then add a little of the venison stew, grate over some more cheese, then cover with another tortilla and fry on both sides.

For the salsa sauce, finely dice the tomatoes, season with salt and pepper, and drizzle over some olive oil. Serve with some sour cream.