Begin by boiling a large pot of salted water over high heat. Add your rotini pasta and cook according to package directions until al dente, about 8-10 minutes. Once done, drain the pasta in a colander and rinse it under cold water.

In a skillet, heat a tablespoon of oil over medium-high heat. Add the ground beef, seasoning with salt and pepper. Cook for about 5-7 minutes until no longer pink, then drain excess fat.

Dice the tomatoes and red onion, and chop the lettuce, keeping them in separate bowls.

In a large mixing bowl, combine the cooled rotini pasta, browned ground beef, shredded cheddar cheese, diced tomatoes, and red onions. Pour in the thousand island dressing and mix until evenly coated.

Fold in the chopped lettuce just before serving. Adjust seasoning to taste and chill in the fridge for at least 30 minutes before serving.