White Queso Sauce - cooking recipe

Ingredients

3 tablespoons butter
1 medium yellow onion, diced small
2 -3 fresh hot chilies, finely diced (jalepenos, serranos, etc) (optional)
3 tablespoons flour
2 cups half-and-half, heated
12 ounces canned diced green chilies (I use 3 - 4 oz cans)
1/2 teaspoon ground cumin
1 teaspoon dried Mexican oregano
1 1/2 cups asadero cheese, 1/2-inch dice
1 - 1 1/2 cup monterey jack cheese, shredded
1 -2 tablespoon shredded fresh cilantro (optional, to taste)
1 -2 cup cooked corn (optional)
6 ounces diced pickled jalapeno peppers (optional)
1 tablespoon fresh lime juice (optional)

Preparation

In a saucepan, saute the diced onions and fresh chilies over medium heat in the butter until onions are soft and transparent.
Add flour and stir/scrape the bottom to prevent sticking. Cook for several minutes to remove the raw flour taste from the roux.
Whisk in the heated half and half until the sauce has thickened (will coat the back of a spoon).
Add the dried cumin, Mexican oregano and drained green chilies and stir to combine.
Add the cheese and stir over medium heat until the cheese has fully melted. Don't use your whisk or the cheese will create a gooey mess in the whisk wires. I use as much Monterey jack cheese as necessary to bring the Queso to the desired consistency.
Once the cheese has melted, add the cilantro, corn, jalepenos and lime juice, if desired. These ingredients are not mandatory but add a great deal of depth to the Queso.
We like to serve this over tortilla chips with thinly-sliced marinated flank steak or chicken breast and diced tomatoes.