Spray a large pan with low-calorie cooking spray and set on a medium heat. Add the onion and garlic, and fry for 5 minutes — until softening.
Add the bacon and sausages and fry for a further 5 minutes, until browned on all sides.
Add the rice and stir. After 2 minutes, add the mushrooms, 100ml of the chicken stock, chopped tomatoes, oregano, chilli flakes, and white wine vinegar.
Stir until the liquid has cooked into the rice, then turn the heat down to a simmer. Keep adding ladlefuls of stock and stirring, allowing each ladleful to be absorbed before adding the next.
Carry on adding stock until the rice is soft, but with a slight bite (this will probably take about 20-30 minutes). Add the spinach and stir until wilted.
Immediately pour into a serving dish, stir in the parmesan and lemon juice, then cover for 5 minutes or so — this will allow the juices to fully soak in. Then serve!