Heat a large skillet over medium-high. Add the ground beef and cook until evenly browned, breaking it up with a spoon.

Drain all the grease except about 3 tablespoons in the pan. Return the beef to the heat, add the taco seasoning, stir until coated, then remove from heat and let cool slightly.

Meanwhile, cook the rotini according to package directions until al dente. Drain and rinse briefly under cold water to stop cooking; drain well.

In a large mixing bowl, combine the cooled pasta, seasoned beef, chopped yellow pepper, diced onion, halved grape tomatoes, shredded cheddar, and shredded iceberg lettuce.

Pour in the French dressing and add the sour cream (reserve a little for garnishing if you like). Toss everything gently until evenly coated.

Fold in most of the crushed Doritos, reserving a handful for topping.

Transfer to a serving bowl, garnish with remaining Doritos and a dollop of sour cream, and serve.