Instant Pot Beef Carnitas

Ingredients

• 2 tablespoons kosher salt
• 2 tablespoons packed brown sugar
• 1 tablespoon ground cumin
• 1 tablespoon smoked paprika
• 1 tablespoon chili powder
• 1 teaspoon garlic powder
• 1 teaspoon ground mustard
• 1 teaspoon dried oregano
• 1 teaspoon cayenne pepper
• 1 boneless beef chuck roast (3 pounds)
• 3 tablespoons canola oil
• 2 large sweet onion, thinly sliced
• 3 poblano peppers, seeded and thinly sliced
• 2 chipotle peppers in adobo sauce, finely chopped
• 1 jar (16 ounces) salsa
• 16 flour tortillas (8 inches), warmed
• 3 cups crumbled queso fresco or shredded Monterey Jack cheese
• Optional toppings: Cubed avocado, sour cream and minced fresh cilantro