Preheat your oven to 375°F (190°C).
In a large skillet over medium heat, add 2 tablespoons of olive oil. Sauté the onion until translucent, about 5 minutes.
Add the pine nuts to the skillet and toast them lightly until golden, for about 2 minutes, stirring frequently to prevent burning.
Stir in the garlic, cinnamon, allspice, and nutmeg, and cook for another minute until aromatic.
Mix in the tomato paste and cook for an additional minute.
Add the rinsed rice to the skillet and stir to coat the grains with the onion mixture.
Pour in water, increase the heat to high, and bring the mixture to a boil. Lower the heat, cover, and simmer until the rice is half-cooked, about 10 minutes.
Remove the skillet from the heat and stir in the currants, parsley, and mint. Season with salt and pepper to taste.
Fill each bell pepper with the rice mixture, leaving room at the top for the rice to expand.
Place the stuffed peppers upright in a baking dish and drizzle the tops with a little olive oil.
Pour a small amount of water into the bottom of the dish to prevent the peppers from sticking and to help steam them as they cook.
Cover the dish with aluminum foil and bake in the preheated oven for 35 minutes.
Remove the foil and bake for an additional 10 minutes, or until the peppers are tender and the tops are slightly browned.
Serve the stuffed peppers warm, garnished with lemon slices.