Start boiling the potato slices in the stock. Start with the stock being cold, then let it come to a boil and then lower the heat to a simmer and let it cook through. The last step takes around 10 to 15 minutes.

Add the oil and butter to a medium-high heat pan, add spices and garlic and cook for around 5 to 20 seconds. (DO NOT BURN THE GARLIC!)

Add the tomato purée to the pan, let it come to a light simmer, then lower the heat to medium-low or medium. Add salt to taste. The sauce is left on a medium-low to medium heat so it reduces and thickens.

(Optional) Add some small spoons of sauce to the broth or some broth to the sauce. This likely doesn't do much, but it might help mix the flavors just a little more.

Once the potatoes are done, drain and add them to the sauce. Mix well. Turn off the sauce's heat.

Serve in a bowl, optionally adding extra sauce beyond what the potatoes are covered in, finish with the crème fraîche.