Brown the chicken thighs in a pan (I tend to do this dry or use 1 tsp of olive oil), then place them in the base of the slow cooker pot.
Add the sliced onions, chopped peppers on top of the chicken, then add the tin of chopped tomatoes, additional cherry tomatoes if you are using them, tomato puree, red wine vinegar and oregano.
Season to taste with salt and pepper.
As you can see this fills my large slow cooker quite well. I used my 5.7 litre slow cooker for this recipe.
Cook for 1 hr on high then 4 on low (or 5-6 hours on low).
Serve with torn fresh basil leaves, with pasta, rice or crusty bread.