Prep the produce
Peel and finely dice the onion. Mince the garlic, slice the cherry tomatoes, roughly chop the parsley, and crumble the feta if it is not already crumbled. Keep everything nearby in little piles so the cooking goes smoothly once the pan is hot.
Mix the yogurt
In a medium bowl, stir together the Greek yogurt, the minced garlic, a pinch of salt, and the juice from half a lemon until smooth and creamy. Taste it and adjust with a little more salt if you want a brighter, punchier yogurt. Set it aside while you cook the rest.
Cook the pasta
Bring a large pot of well-salted water to a boil. Add the pasta and cook for 8-10 minutes, or according to the package directions, until al dente. Drain well and set it aside; if you like a slightly looser final bowl, save a small splash of pasta water before draining.
Cook the lamb sauce
Heat a large skillet over medium heat and add the olive oil. Add the diced onion and cook for 4 minutes, stirring now and then, until softened. Stir in the curry powder, paprika, cumin, a good pinch of salt, and a few grinds of black pepper, and cook for 30 seconds until fragrant. Add the ground lamb, break it up with a spoon, and cook for 5-7 minutes until browned and cooked through. Stir in the tomato paste and cook for 1-2 minutes more, until it darkens slightly and coats the lamb in a rich, glossy sauce.
Make paprika butter
In a small pan, melt the butter over low heat. Stir in the remaining paprika and a pinch of salt for 30-60 seconds, just until the butter turns a deep red and smells toasty; do not let the paprika scorch or it can taste bitter.
Assemble and serve
Divide the pasta among bowls or plates. Spoon over the garlic yogurt, top with the lamb sauce, then scatter over the tomatoes, feta, and parsley. Finish with the warm paprika butter and serve right away while the hot sauce and cool yogurt still contrast beautifully.
