Sheet pan vegetarian fajitas

To cut the onion slices: after peeling, cut the onion in half width wise, so not cutting along the root and stem. Then flip the onion cut side down on the cutting board and slice into ½" slices. Don't overcrowd your sheet pan or the veggies will steam rather than roast. You can fit a lot on a large sheet pan, but don't pile the veggies on. If your sheet pan isn't very large, toss the veggies with the fajita sauce in a large bowl. This is much easier than tossing a lot of veggies on a sheet pan. If you can't find portobello mushrooms, go ahead and use cremini or button mushrooms. Rather than 3 portobellos, go for about 15 cremini mushrooms. Slice them into ½" thick slices. This recipe is vegan with the exception of the topping suggestions. For a vegan option, leave out the sour cream and cheese or use vegan alternatives. For a gluten-free option, use corn tortillas or gluten-free tortillas. We like to use small tortillas and one serving is equivalent to 2 small fajitas. Feel free to use larger tortillas and make larger fajitas. To use frozen peppers, make sure they are already cut into strips. We recommend baking the frozen peppers until they are defrosted and then tossing with the seasoning mixture along with the other veggies. To use store bought fajita seasoning, just make sure you like the flavor. Combine the seasoning with the oil to create the sauce mixture to coat the veggies.