Bangers and Mash with Onion Gravy

Preheat a conventional oven (no fan) to 200°C. Cut the potatoes into approximately 3 cm pieces and thinly slice the onions. Have ready a wide skillet approximately 28 cm in diameter, a pot that holds approximately 4 l, and a small metal baking dish that will fit the sausages in a single layer.

Melt 20 g of the butter in the skillet over medium-low heat, add the onions, and stir. Cover and cook for approximately 10 minutes, then uncover and cook for approximately 25–30 minutes more, stirring every few minutes, until the onions are very soft and golden brown. Stir more often toward the end and lower the heat if the edges begin to darken too quickly. While the onions cook, roast the sausages and cook the potatoes as described in the following steps.

When you remove the lid from the onion skillet, coat the sausages with the 10 ml oil, arrange in the metal dish, and place on the middle rack of the preheated oven. Roast for approximately 30–35 minutes, turning halfway through, until browned and cooked all the way through, with hot, firm filling in the center; if the center is still raw, roast for another 5 minutes. Transfer the cooked sausages to a plate and cover loosely, leaving all the juices and rendered fat in the dish for the gravy. Also save any juices that collect on the plate.

Once the sausages are in the oven, put the potatoes in the pot, add 2000 ml cold water and 8 g salt. Bring to a boil, then simmer gently for approximately 15–20 minutes, until the pieces are completely tender and break apart easily when pressed with a fork. Drain the potatoes, discarding the cooking water, and leave in the colander for approximately 1–2 minutes to let the steam escape.

Heat the milk in the potato pot until hot but not boiling, then turn off the heat. Add the steam-dried potatoes and mash thoroughly with a potato masher, then stir in the remaining 50 g butter, 3 g salt, and half the pepper. Fold with a spatula just until the mash is smooth and fluffy; do not use a blender, which makes the potatoes gluey. Cover the pot and keep warm for a few minutes while you finish the gravy.

Sprinkle the flour over the cooked golden-brown onions and stir for approximately a minute, then gradually pour in 500 ml of the stock, stirring the flour in smoothly without lumps. Heat the remaining 100 ml stock in a small saucepan and pour into the metal sausage dish; scrape up the browned residue with a spatula and pour all the liquid and fat into the onions. Add the bay leaf, 1 g salt, the remaining pepper, and the reserved plate juices. Bring to a gentle boil, then simmer for approximately 6–8 minutes, stirring often, until the gravy thickens slightly and coats a spoon. Remove the bay leaf, add the sausages to the gravy, and heat together for approximately 1–2 minutes.

Divide all the mashed potatoes among four plates and add two sausages to each. Spoon onion gravy over each portion, using all the gravy in the skillet. Serve immediately, while the mashed potatoes are warm and the sausages are hot.