Start your rice first by bringing 4 cups water to a boil in a large pot. Once boiling, add 2 cups rice, stir, and reduce heat to low. Cover and simmer for 18 minutes without peeking—this ensures fluffy, separated grains. The rice will be perfectly tender by the time your meatballs finish cooking.
While rice cooks, combine 1 lb ground beef with 1/2 cup breadcrumbs soaked in 1/4 cup milk, 1 egg, 1/2 tsp salt, and 1/4 tsp black pepper in a large bowl. Mix gently with your hands until just combined—overmixing creates tough meatballs. Roll into 16-18 balls about 1.5 inches in diameter and set on a plate.
Heat 2 tbsp olive oil in a large skillet over medium-high heat. Working in batches, brown the crowd meatballs rice components by searing each meatball for 2-3 minutes per side until golden. Don't crowd the pan—give each meatball space to develop a flavorful crust. Transfer browned meatballs to a plate as you finish batches.
In the same skillet, sauté 1 diced onion for 3 minutes until softened, then add 3 minced garlic cloves and cook 30 seconds until fragrant. Stir in 2 tbsp tomato paste and cook for 1 minute to caramelize slightly, deepening the sauce's flavor profile.
Pour in 1 can (15 oz) tomato sauce, 1 cup beef broth, and 1 tsp Italian seasoning, stirring to combine. Return all meatballs to the skillet and reduce heat to medium-low, simmering uncovered for 8-10 minutes so flavors meld and sauce thickens slightly.
Check that rice is tender and water is absorbed. Fluff rice with a fork and transfer to a serving platter or individual bowls. Top each portion with 3-4 meatballs and generous sauce.