Whisk together eggs, milk and salt in a medium bowl and set aside.

Warm vegetable oil in a nonstick skillet over medium-high heat. Add tortilla strips and cook, stirring occasionally, until strips begin to crisp, about 2 minutes. Add onion and cook until softened, about 3 minutes.

Add egg mixture, Rotel and cheese to skillet. Cook mixture, stirring with a spatula, scraping up cooked eggs and allowing liquid to flow to bottom of pan, until eggs are set, 2 to 3 minutes. Serve immediately.