Bring a large pot of generously salted water to a rolling boil. Add the pasta and cook according to package directions until al dente. Before draining, reserve 1.5 cups of the starchy pasta water. Drain the pasta and set aside.

While the pasta cooks, heat the olive oil in a large skillet or Dutch oven over medium heat. Add the chopped onion and cook, stirring occasionally, until softened and translucent, about 5-7 minutes.

Stir in the minced garlic, tomato paste, and red pepper flakes. Cook for another 2-3 minutes, stirring constantly, until the tomato paste darkens slightly in color and becomes fragrant. This step deepens the tomato flavor significantly.

In a medium bowl, whisk together the full-fat plain yogurt, heavy cream, dried mint, 1 teaspoon of salt, and black pepper until smooth. Ensure your yogurt is at room temperature if possible, to prevent it from curdling when added to the warm pan.

Reduce the heat to low. Gradually add the yogurt mixture to the skillet with the aromatics, stirring continuously until fully combined and smooth. Let it gently simmer for 3-5 minutes, allowing the flavors to meld and the sauce to warm through, being careful not to let it boil.

Add the cooked, drained pasta to the skillet with the sauce. Pour in 0.5 cup of the reserved pasta water. Toss everything together, coating the pasta evenly. If the sauce seems too thick, add more pasta water, a tablespoon at a time, until it reaches your desired consistency. Continue to cook for 1-2 minutes, allowing the pasta to absorb some of the sauce.

Taste and adjust seasoning if needed. Serve immediately, garnished generously with fresh chopped parsley or dill.