Preheat the oven to 375F

Add potatoes to a pot of water with a pinch of salt, bring to the boil, and then boil for 5-minutes. Remove from the heat, drain, and cool before cutting them into halves or quarters.

Add bacon to a cast-iron skillet (you can use a little cooking spray first if you like). Cook evenly on both sides until cooked, but not crispy. Remove from the pan and pop on paper towels to remove excess oil and cool before dicing.

Add sausage to the bacon fat in the skillet and cook completely. Again, remove from the pan and pop onto paper towels to drain excess oils.

Add the onions to the skillet and cook those in the bacon fat too. Once translucent, add the potatoes back to the pan, toss to coat with the bacon fat, and then add the diced bacon and sausage back to the skillet as well. Reduce the heat to simmer.

Combine the mustard, vinegar, garlic, pepper, sugar, and thyme in a small jug and pour over the potatoes. Toss until everything is coated. Remove the skillet from the heat and transfer to the oven for approximately 15-minutes.