Pre-heat your oven to 400°F (200°C).
Fill a small saucepan with 1.5 cups of water and the cup of rice. Cover with a lid and place over a high heat and bring to boil. Reduce to a simmer and leave over a low heat until the water has evaporated and the rice is cooked.
Meanwhile, prick the peppers all over with a fork, and microwave on high for 5 minutes until soft but not falling apart.
Place a large skillet over medium heat and add the olive oil. When the oil is hot, add the onion and saute until soft and translucent (about 4 minutes). Add the garlic, paprika, and cumin and saute for another minute.
Next, add the ground pork to the pan and saute, stirring often, for another 5 minutes or until nicely colored all over. You can add a splash of water to the pan if it looks too dry.
Pour the can of tomatoes into the pan and add the tomato paste/sofrito. Stir to combine and simmer for another 5 minutes until it has reduced slightly. Remove from heat and stir in the rice. Season with salt and pepper.
Stand the peppers upright in a large baking tray, and split the rice-pork mixture evenly among them. Don't overfill, leave a little room at the top. Place the pepper tops back on and bake in the oven for 15-20 minutes until the filling has reduced and is no longer runny. Serve by themselves as an appetizer or tapas, or with a salad or potatoes for a light main.