2 tablespoons canola oil, divided
1 tablespoon fresh lime juice
1 teaspoon brown sugar
1 1/2 teaspoons chipotle chile powder
2 large garlic cloves, minced and divided
1 (1-pound) skirt steak, trimmed and chopped
1/2 medium onion, cut into 1/2-inch-thick slices
1/2 pound plum tomatoes, halved lengthwise
1 red bell pepper, halved and seeded
5/8 teaspoon salt, divided
1/4 teaspoon dried oregano
1/4 teaspoon freshly ground black pepper
Cooking spray
8 (6-inch) corn tortillas
1/4 cup reduced-fat sour cream