Heat oven to 400°

Wipe mushrooms clean + thinly slice; heat 1 tbsp oil in skillet over high, cook undisturbed 3 min; sauté 3-4 min until browned + tender, season with salt/pep

In batches, heat 4 tortillas in skillet over med-high, 30 sec or until warm

Divide the mushrooms + potatoes among tortillas, roll up + place in a small, lightly oiled baking dish seam side down; drizzle on 1 container of sauce

Cover dish with foil + bake 10 min; remove foil + bake 7-10 min more uncovered until hot + bubbling

Cut onion in half from root to stem, peel + thinly slice ½ (or whole) of onion; garnish enchiladas with onion divide to plates