Heat some oil in a pan.
Add onions and carrots and cook for 5 minutes until they start to soften.
Put the beef in the pan and cook for 5-10 minutes until it browns, breaking it up as it cooks.
Stir occasionally to avoid sticking, but not too much.
Add mushrooms and cook for a few minutes.
Sprinkle in flour, mix well, and cook for 3-4 minutes to thicken.
Pour in canned tomatoes, add a stock cube, and bring to a boil while stirring.
Reduce heat and simmer for about 10 minutes until it thickens.
If it’s too thick, add a bit of boiling water.
Preheat your oven to 400°F / Gas Mark 6.
Mix Worcestershire sauce into the meat and put it in a dish, smoothing the top.
Soften and spread potatoes over the meat, score the top with a fork, and add some butter.
Bake in the center of the oven for 20-30 minutes until the pie is golden and bubbling.