- Using a small sharp knife, peel and chop the onions, carrots and celery. Peel the garlic and use a garlic rusher or grate on the fine side of a box grater.
- Heat a large non-stick frying pan over a medium heat. Add half of the butter and once it is melted, tip in the onion, carrots, celery and garlic, stirring to combine. Cook for about 5 minutes until softened, stirring occasionally with a wooden spoon.
- Add the steak mince to the pan and cook for another 3-4 minutes or until browned, stirring occasionally and break up any lumps with a wooden spoon. Stir in the flour and cook for 1 minute.
- Then stir in the tomato puree and allow to cook for a further minute before adding the stock and worcestershire sauce. Bring to a simmer and then cook for 10 minutes until thickened, stirring occasionally. Stir in the frozen peas and place the mixture in an ovenproof dish.
- Preheat the oven to 180°C/ 350°F/ Gas Mark 4.
- Peel the potatoes and cut into dice. Steam the potatoes in a saucepan for 10-12 minutes until tender. To check if they are ready, pierce with the tip of a sharp knife and you should feel so resistance. Tip into a bowl and mash with a potato masher until smooth. Season with salt and pepper and beat in the rest of the butter and milk.
- Spoon the mash on top of the mince, starting with dollops around the edges and finishing in the middle. Spread around with a table knife until you have a nice even layer and then bake for 30 minutes until bubbling and golden.
- Steam sugar snap peas for 1-2 minutes until tender and serve along with the shepherd's pie.