Put the peppers, cut-side down, on a plate and microwave on High for 4 mins until cooked through (but not so soft they collapse). If they need longer, microwave for 1 min more and repeat until done.
Put the pork in a cold frying pan and turn on the heat. Fry, breaking up any lumps, until it starts to brown. Stir in the garlic and spices for 1 min, then add the bulghar and stock. Cover and simmer for 10 mins until the bulghar is soft.
Heat the grill. Stir half the parsley into the bulghar, then stuff into the peppers on a baking tray. Grill to crisp, sprinkle over most of the parsley, then serve with the yogurt mixed with remaining parsley.