Squeeze the sausages out of their skins, and roll the sausagemeat* into 12 bite-size balls
Heat ½ tablespoon of the oil in a 20cm ovenproof frying pan. Add the sausage balls and fry all over for 1 minute, until browned and cooked through. Add the bacon and mushrooms and fry for a few minutes, until golden. Add the tomatoes and cook for a further minute. Tip the mixture into a bowl and set aside. Discard excess fat from the pan.
Whisk together the eggs and dried herbs and season with freshly ground black pepper. Stir in two thirds of the fried sausage mix. Preheat the grill to medium.
Heat the remaining oil in the frying pan over a medium heat. Add the egg mixture, tipping the pan so that it covers the base. Turn down the heat and scatter over the remaining sausage mixture. Cook for 8 minutes, or until almost set.
Place under a preheated grill for 2-3 minutes, until the frittata is set and golden. Let cool slightly, then slide out of the pan, cut into wedges and serve.
*Always wash hands after handling raw meat.