In a large saucepan, heat the oil. Add the onion and cook for 5 minutes the add the mince, stirring, until browned all over. While the meat is frying, break up any lumps with the back of the spoon. Add stock cube and bay leaves.
Add tomato, spring onions, carrot, Worcestershire sauce, chilli flake and sriracha sauce. Mix well
For the mash, boil the potatoes until tender. Drain, add the milk, butter and egg yolk, then mash until smooth. Season with salt and pepper.
Pour the meat into a ovenproof dish and spread the mash on top, smooth over and mark with a spatula.
Use a fork scroll lines pattern on your mash. Put the dish into the oven and cook until the surface is golden-brown fir 20-25 min
Take it out and egg wash the surface, put back in oven for another 5-8 min