Step 1

Heat 1 tbsp olive oil in a large, shallow, flameproof casserole dish set over a medium heat. Fry 1 chopped onion, 1 chopped leek, 1 chopped celery stalk and 3 diced large carrots for 10 minutes, stirring frequently, until starting to soften. Add 2 grated garlic cloves and 2 tbsp thyme leaves, then push the vegetables to the edge of the pan. Increase the heat, add 500g minced lamb or beef and fry for five minutes until brown, breaking it up with a wooden spoon as you go. Sprinkle over 1 tbsp plain flour and cook for a further minute.

Step 2

Throw 2 fresh or dried bay leaves into the pan, then stir in 1½ tbsp miso, 1 tbsp dark soy sauce, 1 tbsp tomato purée, 2 tsp fish sauce and 200ml water. Bring to a simmer and cook for 20 minutes. Remove the dish from the heat and allow to cool for about 10 minutes. (You can cool completely and freeze the meat mixture at this point.)

Step 3

Preheat the oven to 200C/180C fan/gas mark 6.

Step 4

In a separate saucepan, heat 900g mashed potato with 3 tbsp whole milk and 1 tbsp butter, stirring until smooth and warmed through. Top the cooled meat mixture with the mashed potato and rough up the surface with a fork. Scatter over 100g grated strong cheddar cheese and cook in the oven for 20 minutes, or until golden and bubbling. Once assembled, this will sit happily in the refrigerator for two days before cooking, and the meat sauce will keep in the freezer for up to two months.