Ingredients

Equipment Needed

• •Large non-stick frying pan for the sausages
• •Wide, heavy-bottomed pan for the onion gravy
• •Large saucepan for boiling potatoes
• •Potato masher

Instructions

1. 1

   Start the onion gravy

   Melt the butter in a wide, heavy pan over a low heat. Add all the sliced onions and a generous pinch of salt. Stir them through the butter, then leave them alone. This isn't quick cooking. You want the onions to go from sharp and white to soft and translucent, then slowly on to deep golden and sticky. Stir every few minutes, scraping up anything that catches on the bottom. It takes a good twenty-five to thirty minutes. Don't rush them. The sweetness only comes with patience, and that sweetness is the whole gravy.

   If the onions start to catch or colour too fast, add a splash of water and lower the heat. You're coaxing, not searing.
2. 2

   Soften the leeks

   While the onions do their slow work, melt a knob of butter in a smaller pan. Add the sliced leeks and a pinch of salt. Cook them gently for five or six minutes until they're soft and silky, with no colour. They should smell sweet and grassy. Take them off the heat and let them cool for a few minutes. Warm leeks in the mix are fine. Hot leeks will melt the cheese before you want it to.

3. 3

   Mix and shape the sausages

   In a large bowl, combine the breadcrumbs, crumbled cheese, softened leeks, parsley, thyme leaves, and mustard. Season with salt and pepper. Add the egg yolks and work everything together with your hands until it holds when you squeeze it. It should feel like damp sand that just about sticks. If it's too dry, add a splash of milk. If too wet, a handful more breadcrumbs. Divide the mixture into eight and roll each into a fat sausage shape. Put the flour on one plate, the lightly beaten egg whites on another, and the extra breadcrumbs on a third. Roll each sausage in flour, then egg white, then breadcrumbs. Set them on a board. They'll firm up while you deal with the potatoes.

   If you have time, put the shaped sausages in the fridge for twenty minutes. They hold together better when they hit the hot pan cold.
4. 4

   Boil the potatoes

   Put the potato chunks in a large pan of cold, well-salted water. Bring to the boil, then simmer for fifteen to twenty minutes until a knife slides through without resistance. Don't let them fall apart. Drain well and leave them in the colander for a minute or two so the steam escapes. Wet potatoes make gluey mash.

5. 5

   Finish the gravy

   By now the onions should be deep amber and sweet. Strip the thyme leaves from their sprigs and stir them in. Sprinkle over the flour, stir it through, and cook for a minute until the raw flour smell has gone. Pour in the stock gradually, stirring as you go, and bring to a gentle simmer. Let it cook for ten minutes until it thickens into a proper gravy, not thick like paste, but with enough body to pool on the plate and stay there. Add the vinegar. Season and taste. The vinegar sharpens the sweetness and stops it being one-note. Keep it warm on a low heat with a lid ajar.

6. 6

   Fry the sausages

   Heat a knob of butter and a splash of oil in a large frying pan over a medium heat. When the butter foams and starts to calm down, lay the sausages in. Don't crowd them. Give them space to colour properly. Fry for eight to ten minutes, turning them gently every couple of minutes, until they're golden and crisp all over. The breadcrumb coating should be deep gold and feel firm when you press it. Lift them onto a warm plate.

   Use a mix of butter and oil. The butter gives flavour; the oil stops it burning. If the pan gets too hot and the butter darkens, pull it off the heat for a moment.
7. 7

   Mash and serve

   Return the drained potatoes to their warm pan. Add the butter, let it melt into them, then mash until smooth. Add the warm milk a little at a time, working it in until the mash is soft and giving but not sloppy. Season with salt. Taste it. Mash that needs salt is just hot potato; mash with enough salt is comfort. Spoon a generous pile of mash onto each warm plate. Lean two sausages against it. Ladle the onion gravy alongside, letting it pool around the base. There are few better feelings than putting a plate like this in front of someone on a cold evening.

Chef Tips

• •Caerphilly is the right cheese here. It crumbles rather than melts, which is what you want: pockets of sharp, salty cheese inside the sausage, not a uniform paste. If you can't find it, use Lancashire or a young, crumbly Cheshire. Avoid anything that stretches when it melts. Cheddar is too smooth for this.
• •The coating is worth doing properly: flour, then egg white, then breadcrumbs. Each layer has a job. The flour dries the surface. The egg white gives the crumbs something to grip. The crumbs give you the crisp. Skip a step and the sausages fall apart in the pan.
• •Your onion gravy will only be as good as your patience with the onions. Low heat, plenty of time, and resist the urge to turn it up. The difference between onions cooked for fifteen minutes and onions cooked for thirty is the difference between a sauce and a gravy worth mopping up with bread.
• •This is a good budget supper. Leeks, cheese, breadcrumbs, onions, potatoes. None of it is expensive. All of it, treated well, adds up to something that feels generous and complete. A recipe is a conversation, not a contract. If you've got sage instead of thyme, use sage. If the leeks are enormous, use one. Your kitchen, your rules.

Advance Preparation

• •The sausages can be shaped, coated, and refrigerated up to a day ahead. They actually fry better from cold, holding their shape more confidently in the hot pan.
• •The onion gravy improves overnight. Make it the day before if you have the foresight, and reheat gently. The flavours settle and deepen.
• •The mash is best made fresh. Cold mash reheated is a different, lesser thing.

Frequently Asked Questions

Nutrition Information

1 serving (about 550g)