Step 1

Peel the potatoes, then dice them into large even-sized chunks. For reference, I consider a 9oz/250g potato to be a medium/large potato, of which I quarter. For smaller potatoes consider slicing them into 2 or 3 (they will shrink down somewhat as they cook). Preheat oven to 410F/210C.

Step 2

Place the potatoes in a pot and fill with cold water until just about covered. Add in 2 tsp salt and bring to a full rolling boil. Once boiling, cook the potatoes for 6-8mins, or until they are just about knife tender, but not so much that they begin breaking apart. The edges should start to rough.

Step 3

Drain in a colander (do not rinse) and give them a shake to rough the edges. Allow them to steam dry for 8-10mins. The more they steam = the more moisture is leaving the potatoes = the fluffier they'll be. During this time, spread the goose fat in a large baking dish and place it in the oven. The fat should comfortably cover the base of the dish.

Step 4

Mix 1 heaped tsp (not tbsp!) flour with 1/2 tsp salt in a small pot to one side. Sprinkle over the potatoes, shaking a little more to ensure they’re evenly coated. Leave for a further 2mins to allow the flour to 'glue' to the potato and form a crust.

Step 5

When the goose fat is smoking hot (literally) very carefully add the potatoes to the dish, ensuring they’re evenly spaced out. Add garlic and rosemary and stir to coat everything in the fat. Work quickly so the fat stays hot, just be careful of the fat spitting out the pan.

Step 6

Place in the oven for a total of 50-60mins or until deep golden and visibly crispy. Take out and flip/re-coat in fat 2-3 times throughout to ensure an even coverage. Ovens will run slightly differently, so just be vigilant. It's unlikely they'll be done before 50mins, but don't be afraid to run over the hour until they're ultra-crisp.

Step 7

Serve with a sprinkle of sea salt to draw out the final bit of moisture, just for extra crispiness.