Sheet-Pan Portobello Fajitas

Whisk oil, chili powder, chipotle powder, cumin, onion powder, garlic powder, 2 tablespoons lime juice and 1/2 teaspoon salt together in a large bowl. Add mushrooms; toss to coat. Cover, and let marinate at room temperature for at least 20 minutes or up to 2 hours. (Alternatively, refrigerate for up to 8 hours.) 

Preheat oven to 425°F. 

Add onion and bell peppers to the mushroom mixture in the bowl; toss until well combined. Spread the mixture on a large rimmed baking sheet. Roast until tender, 20 to 25 minutes. Remove from oven. (Do not turn the oven off.)

Meanwhile, combine yogurt, avocado, serrano, garlic and the remaining 3 tablespoons lime juice and 1/2 teaspoon salt in a food processor; process until smooth and creamy, about 30 seconds. Cover and refrigerate until ready to use.

Wrap tortillas all together in foil. Place in the oven until warmed through, about 3 minutes.

Serve the fajita mixture with the warmed tortillas and avocado crema. Garnish with cilantro, jalapeños and/or queso fresco, if desired.