Combine all of the steak marinade ingredients in a high speed blender and pulse until combined. Place steak in a covered dish and pour in marinade, making sure to coat all sides. Set aside while you make everything else.

Next, heat your 3 tablespoons of olive oil in a skillet over medium-high heat. Once the oil is hot and shimmering, add the onion and bell peppers. Let them cook, stirring semi-frequently, until they are soft and slightly charred. Do not burn.

While your onions and peppers are cooking, add all cheese sauce ingredients to a small sauce pan over medium heat, whisking occasionally until cheese is fully melted and all ingredients are combined. Add more milk if you need to thin it out. Keep warm, stirring occasionally, until ready to use.

Once the onions and peppers are done, remove them from the skillet and keeping it over medium-high heat, add your steak. Cook for about 2 minutes per side or until just slightly pink in the middle (or until desired doneness). Thinly slice the steak once cooked.

NOTE: You can also use a grill pan or a gas grill for the steak if you want to get pretty grill lines on your steak.

Add tortilla chips to platter, and top with cheese sauce, peppers, and steak strips. Sprinkle on cilantro for garnish. Serve with sour cream, salsa, and guacamole on the side.