Saute chorizo in a large saute pan over high heat until cooked through and crispy, about 10 minutes, crumbling and stirring with a spoon constantly. Remove from heat and set aside.
While the chorizo is cooking, melt the butter in a separate medium saucepan over medium-high heat. Whisk in the cornstarch until combined and cook for 1 minute, stirring constantly. Add the evaporated milk, and whisk until combined and smooth. Add in half of the cheese, and stir until melted. Repeat with the second half of the cheese. Stir in the green chiles, tomatoes, and cooked chorizo until combined.
Taste the queso, and season with your desired amount of salt. Serve immediately with chips.
Mothers Secret Recipes of Comfort Food & Culinary Inspiration from an Organic and Allergen-free Approach