• Gather all ingredients and equipment.

For Meatballs:

• Finely dice 3/4 of the white onion and mince the four cloves of garlic for the meatball mixture.
• Heat 2 tablespoons of vegetable oil in a frying pan over medium-high heat. Add the diced onion, minced garlic, and ground cumin; cook, stirring occasionally, until softened and aromatic, about 4–5 minutes. Season with salt and pepper, then remove from the heat and let cool slightly.
• In a large bowl, combine the ground beef, egg, cooled onion mixture, breadcrumbs, Greek yogurt, and a pinch of salt and pepper. Mix gently until just combined—avoid overworking the meat.
• Shape the mixture into golf-ball-sized meatballs and set them aside on a plate.
• Heat the remaining 2 tablespoons of vegetable oil in a skillet over medium-high heat. Working in batches so you don't overcrowd the pan, brown the meatballs about 2 minutes per side until nicely seared. Transfer browned meatballs to a plate.

For Pasta:

• Bring 4 quarts of water to a boil in a large pot. Stir in 1/4 cup of salt, add the fettuccine, and cook until about 3 minutes shy of the package's recommended time so the pasta remains slightly underdone.
• Before draining, reserve 1 cup of the starchy pasta cooking water. Drain the pasta and set aside.

For Sauce & Assembly:

• In the skillet used earlier or a heavy pot, warm 2 tablespoons of olive oil over medium heat. Add the remaining 1/4 diced onion and 2 minced garlic cloves; cook until softened, about 2 minutes.
• Add the entire tube of tomato paste and cook, stirring frequently, until it darkens and develops a deeper flavor, roughly 5 minutes.
• Gradually stir in reserved pasta water, a little at a time, until the sauce loosens to a smooth, saucy consistency that will coat the pasta.
• Using tongs, add the drained fettuccine to the sauce and toss to coat. Nestle the browned meatballs into the pasta, adjust seasoning with salt and pepper to taste, and warm briefly so everything comes together.
• Serve immediately topped with grated Parmesan cheese.