3 tablespoons vegetable oil
50g (about 3 ½ tablespoons) butter
1 large onion, thinly sliced
2 leeks, sliced
About 250g (½ lb.) leftover cooked potatoes, roughly diced
About 200g (7 ounces) leftover cooked carrots, diced
About 200g (7 ounces) leftover cooked brussels sprouts, cut in half
3 teaspoons chopped parsley
125g (4.4 ounces) Stilton cheese, roughly crumbled
Melt 2 tablespoons of the vegetable oil and 20g of the butter in a large frying pan. Add the onion and cook for about 10 minutes, until softened and beginning to caramelize a little.
Stir in the leeks and a sprinkling of salt and cook until tender and lightly caramelized. Remove the onion and leeks from the pan with a slotted spoon and set aside.
Heat the remaining oil and butter in the pan, then add the potatoes and cook over a medium heat until a golden crust forms underneath.
Turn them over, add the carrots and brussels sprouts and cook, stirring occasionally, until the potatoes are golden all over and the carrots and sprouts are beginning to caramelize. Return the onion and leeks to the pan, add the parsley and toss together thoroughly. Season to taste, then stir in the crumbled Stilton so it begins to melt.