Prep all ingredients per instructions above.
Prepare Homemade Queso: In a saucepan, melt butter over medium heat. Add all-purpose flour and whisk constantly for 1-2 minutes until it forms a roux (paste).
Gradually whisk in milk until the mixture thickens. Reduce the heat to low and add shredded cheddar cheese, chili powder, cumin powder, and a pinch of salt. Continue to stir until the cheese is fully melted and the queso is smooth and creamy.
Prepare the Steak: Season the sirloin steak with salt and pepper to taste. Heat a grill or grill pan over medium-high heat and lightly oil it.
Grill the steak for about 4-5 minutes per side or until it reaches your desired level of doneness (medium-rare, medium, etc.). Remove the steak from the grill and let it rest for a few minutes before slicing it thinly.
Assemble the Burritos: Lay out the flour tortillas. Divide the sliced grilled steak evenly between the tortillas. Add onions, tortilla strips, bell peppers, and tomatoes.
Fold and Grill: Fold in the sides of each tortilla and then roll them up tightly, securing the ends. Top with cheese and place under the oven broiler to melt.
Serve: Slice each burrito in half and serve with a dollop of sour cream and salsa on the side.
Enjoy: Sit down and savor your grilled steak and cheese burrito with homemade queso, chips, and a refreshing glass of kombucha.