Place the new potatoes into a large saucepan, cover with cold water then add in a large pinch of salt. Cover the pan with a lid then set over a high heat.
Bring the water to the boil then lower the heat slightly & simmer until the potatoes are tender. This will roughly take between 15-20 minutes.To check if the potatoes are cooked, insert the tip of a knife into a potato. It should go in with very little resistance. Whilst the potatoes are cooking, preheat an oven to 220°c/200°c fan (428°f/392°f). At the same time, crush the garlic with the side of a knife & set to one side.Don't worry about peeling the garlic! Once the potatoes are cooked, drain them through a colander then leave to steam dry for 5 minutes or so. Then in the meantime, add the goose fat & vegetable oil into a large roasting tin then place in the oven & leave to get smoking hot.
Place the new potatoes onto a large baking tray (or chopping board) then use a potato masher, saucepan or something heavy to crush them one at a time, so that they're flat but still in one piece.
Next, take the tray of hot fat out of the oven then use a pair of tongs to carefully transfer the crushed potatoes into the tray, turning them gently to completely coat in fat.
Add the crushed garlic into the tray, season the potatoes with sea salt & freshly cracked black pepper then roast for 35-40 minutes until crispy. Flip the potatoes over after 20 minutes then add in the herbs & continue roasting.
Once cooked, hit the potatoes with some more seasoning then serve!