0 Bring a large pot of heavily salted water to a boil. Add the pasta and cook according to package directions for al dente. During the final 2 minutes of cooking, add the peas. Reserve 1 cup of the pasta water; drain.
1 Meanwhile, add the yogurt, 2 tablespoons of the oil, half of the lemon zest and juice, mint, garlic, 3/4 teaspoon salt, and several grinds black pepper in the bowl of a food processor fitted with the blade attachment. Process on low speed until blended, about 30 seconds. Set aside.
2 In a separate small bowl, add the remaining lemon zest and feta and stir until combined. Set aside.
3 Let the drained pasta sit for about 1 minute, then return it to the pot. Slowly add the yogurt-mint sauce, stirring continuously. Add the reserved pasta water a little at a time until the sauce evenly coats the noodles.
4 Taste and adjust with more lemon juice, salt, or black pepper, to taste. Set over low heat to keep warm.
5 Add the pine nuts, chili flakes, and remaining 1 tablespoon oil to a small skillet. Heat over medium-low heat and cook, stirring, until the nuts are golden, 1½ to 2 minutes (watch carefully so they don’t burn). Pour the nuts and the oil over the crumbled feta and stir to combine.
6 Divide the pasta into bowls. Spoon the spicy feta and any reserved oil over each serving.
