Set up your Q for direct cooking. Place the Weber Ware Casserole Dish (without the lid) at the back centre of the Q and add the oil. Preheat on high for 10 minutes.
Lightly oil the pork and season with salt and pepper.
Once the Q is preheated, leave the heat setting on high. Add the onions to the casserole dish, season with salt and pepper, and cook, stirring occasionally, for 5 to 6 minutes. At the same time, add the pork to the grill around the casserole dish. Cook for 2½ to 3 minutes per side, 5 to 6 minutes in total. Just before the pork is ready, add the garlic and chillies to the onions and cook for 1 minute. Then add the pork to the casserole along with the paprika and 100ml of the water. Stir well. Move the casserole dish to the centre of the Q and cook for a further 8 to 10 minutes. By this stage, the liquid should have reduced by half.
Remove the casserole dish from the Q. Add the tomato paste, capsicums, fennel seeds, vinegar, salt to taste, and the remaining 500ml of water.
Turn the Q to the roast setting and add a convection tray and trivet using tongs and/or wearing heatproof gloves.
Place the lid on the casserole dish (turn the vent control to steam) and place on the trivet. Cook for 1½ to 1¾ hours.
In a bowl combine the sour cream, parsley, and lemon zest.
Remove the casserole dish from the Q. Serve the pork with the sour cream mixture and thick slices of grilled crusty bread, if desired.