For the burritos:
1 tablespoon canola oil
1 large onion, diced
1 pound ground beef or sirloin
3 cloves garlic, minced
1 tablespoon tomato paste
1 can black beans, drained and rinsed
¼ cup water
½ teaspoon cumin
½ teaspoon oregano
1¼ teaspoons chili powder
⅛ teaspoon cayenne
1 teaspoon brown sugar
1 cup shredded monterey jack cheese
4-10 tortillas, depending on size (4-5 for burrito-sized, more for soft taco or fajita sized)
Cooking spray
For the sauce:
2 poblano peppers
2 tablespoons butter
1 jalapeño pepper (optional)
2 tablespoons flour
⅔ cup chicken broth
½ cup sour cream (light is fine)
Heat oven to 400º and lightly grease a baking sheet with cooking spray. Heat a large skillet over medium heat, then add the oil. Once the oil is hot, add the onion and cook for 3-5 minutes or until the onion begins to soften. Add the ground beef and break up with a wooden spoon. Continue cooking until the meat is cooked through, then drain off any fat if necessary. Add the garlic and tomato paste and cook for about a minute. Stir in the beans, water and spices and add salt to taste. Reduce heat to a simmer and cook until most of the liquid has been absorbed.
Place about 2 tablespoons (or more, depending on size) of cheese at the end of each tortilla. Top with a generous amount of the beef and bean mixture. Roll into a burrito by folding the left and right sides in and then rolling away from you. Place the burrito seam-side down on the baking sheet and repeat process with remaining tortillas, cheese and filling. Lightly spray with cooking spray, then bake for about 20 minutes until the tortillas are golden and crisp.
Meanwhile, prepare the sauce. Roast the poblanos, either directly over a gas flame or under the broiler, until the skin is charred. Place in a small bowl and cover with plastic wrap until cool enough to handle. Peel the peppers, remove the stem and seeds and dice.
In a small saucepan set over medium heat, melt the butter. Once butter has melted, whisk in flour and cook for an additional minute, whisking constantly. Slowly whisk in the chicken broth and then add the poblano peppers. Continue to simmer, whisking frequently, until sauce has thickened. Stir in the sour cream and add salt and pepper to taste. Heat through, then spoon sauce over the burritos.