Preheat your oven to 190°C.
Slice the top off the red bell pepper and carefully remove the seeds and membranes from the inside.
Finely dice the onion and mince the garlic clove.
In a non-stick skillet over medium heat, sauté the onion and garlic until they become soft and translucent.
Add the ground beef to the skillet and cook until fully browned, breaking it into small crumbles with a spatula.
Stir the cooked rice, 50ml of the tomato puree, dried oregano, 0.25 tsp salt, and black pepper into the beef mixture.
Pack the beef and rice mixture tightly into the hollowed bell pepper.
Place the stuffed pepper upright in a small baking dish and pour the remaining 50ml of tomato puree over and around it.
Cover the dish with foil and bake for 25 minutes, then remove the foil and bake for another 5-10 minutes until the pepper is tender.
While the pepper bakes, thinly slice the cucumber into rounds.
Whisk together the olive oil, apple cider vinegar, chopped fresh dill, and the remaining 0.25 tsp salt in a small bowl.
Toss the cucumber slices in the dressing and let them marinate in the refrigerator until the pepper is ready.
Serve the hot stuffed pepper on a plate alongside the chilled, zesty cucumber salad.