Melt 2 Tbsp. butter in a large heavy saucepan over low heat; add chopped green chiles and minced onion, and cook 3 to 4 minutes or until softened. Whisk in 2 Tbsp. flour, and cook 1 minute. Whisk in milk and beer, and cook, whisking constantly, 3 to 4 minutes or until mixture is thickened. Add shredded cheese by 1/2 cupfuls, stirring until melted after each addition. Stir in ground cumin and salt. Serve warm with tortillas chips.
If you don't like beer don't make this. If you do, use a good beer and you won't be disappointed! I used Sharp Cheddar (about 2 1/2 cups) instead and was very pleased with the unique flavor of this queso. I will make this again.