Grill sausages, about 15 minutes, then cut each sausage into quarters.
While sausages are grilling prep the vegetables.
Heat the olive oil in a frying pan and sauté the onion and garlic until soft, about 4 minutes. Then add to the slow cooker.
Add the rest of the prepared vegetables, the sausages and tin of tomatoes to the slow cooker.
Stir in the tomato puree, stock and oregano.
Cook on low 4 to 5 hours until the vegetables are soft. Stir occasionally whilst cooking.
Switch off the power, stir in the frozen peas and leave to sit for 10 – 15 minutes until the peas are cooked through.
Serve over some whole wheat fusilli pasta.