Preheat your oven to 400°F (200°C). Line a large rimmed baking sheet or a 9x13-inch baking dish with parchment paper or lightly oil it.

Halve the bell peppers lengthwise through the stem. Remove all seeds and white membranes. Brush the cut surfaces and outside of each pepper half lightly with olive oil and season the insides with a pinch of salt and black pepper.

Place the peppers cut-side down on the prepared baking sheet and roast for 10 minutes until slightly softened and beginning to caramelize at the edges. Remove from the oven and flip cut-side up. Set aside while you make the filling.

Heat 2 tablespoons of olive oil in a large skillet over medium-high heat until shimmering. Add the diced onion and a pinch of salt. Cook, stirring occasionally, for 4–5 minutes until softened and golden at the edges.

Add the minced garlic and cook for 60 seconds until fragrant. Stir in the tomato paste and cook for another 60 seconds, pressing it against the pan until it deepens in color slightly.

Add the ground turkey to the skillet. Break it up with a wooden spoon and cook over medium-high heat for 6–7 minutes, stirring occasionally, until it is mostly browned with some golden caramelization on the meat. Do not overcrowd or stir constantly — let it develop color.

Add the smoked paprika, cumin, dried oregano, garlic powder, red pepper flakes (if using), salt, and black pepper. Stir to coat the meat evenly in the spices and cook for 1 minute until the spices are fragrant and toasted.

Add the drained diced tomatoes to the skillet. Stir to combine and cook for 3–4 minutes until most of the liquid has reduced and the mixture is thick and saucy, not wet.

Remove the skillet from the heat. Fold in the cooked quinoa and half of the crumbled feta. Taste the filling and adjust salt, pepper, or spices as needed. The filling should taste boldly seasoned.

Arrange the pre-roasted pepper halves cut-side up in the baking dish. Spoon the turkey and quinoa filling generously into each pepper, mounding it slightly above the rim — do not underfill.

Sprinkle the remaining crumbled feta evenly over the top of each stuffed pepper.

Bake in the 400°F oven for 18–22 minutes until the peppers are fully tender, the filling is heated through, and the feta on top is golden at the edges.

Remove from the oven and let rest for 5 minutes. Squeeze fresh lemon juice over the peppers immediately out of the oven.

Garnish generously with fresh chopped parsley and mint leaves if using. Serve directly from the baking dish, two halves per person.