Heat 1 tablespoon olive oil over medium-high heat in a large heavy-bottomed pot or Dutch oven until shimmering. Add 1 diced medium yellow onion and cook until softened, about 5 minutes. Add 1 pound ground beef and cook, breaking up the meat into smaller pieces with a wooden spoon, until browned, 5 to 7 minutes.
Stir in 1 tablespoon tomato paste, 2 minced garlic cloves, and 1 (1-ounce) package taco seasoning. Cook until the tomato paste is darkened in color and the mixture is fragrant, about 1 minute.
Stir in 1 (32-ounce) carton low-sodium beef broth, 1 (10-ounce) can diced tomatoes with green chiles, and 1 pound dried rotini pasta. Fill the diced tomato can up with water and pour that into the pot. Bring to a simmer. Continue to simmer, stirring occasionally so the pasta doesn't stick, until the pasta is al dente, about 10 minutes. Turn off the heat.
Stir in 4 ounces shredded Monterey Jack cheese and 3 tablespoons chopped fresh cilantro leaves. Taste and season with salt as needed. Garnish with more cilantro, sour cream, and sliced pickled jalapeños if desired.
