Bring a large pot of salted water to a boil. Cook the pasta until al dente according to package instructions. Drain and rinse briefly under cold water to cool. Set aside.

Heat the olive oil in a large skillet over medium heat. Add the onion and cook for 3-4 minutes, until softened. Add the ground beef and cook for 6-8 minutes, breaking it up, until browned and cooked through. Stir in the water, tomato paste, taco seasoning and salt. Simmer for 2–3 minutes until saucy and well combined. Remove from heat and let cool slightly.

In a large bowl, whisk together the salsa, sour cream, and lime juice until well combined.

Add the cooked pasta, taco meat, black beans, corn, shredded cheese, tomatoes and green onions to the bowl. Toss until everything is evenly coated. Taste and adjust seasoning as needed. Serve right away or refrigerate for up to 2 hours before serving.