Gluten Free Green Bean Casserole

1 lb canned or fresh green beans (rinsed, trimmed and halved)
2 Tbsp. unsalted butter (for dairy free use dairy/gluten free butter)
2 large portabella mushrooms (sliced)
1/2 tsp. freshly ground black pepper
1/3 C sour cream (For Dairy Free use Soy Milk)
2 Tbsp gluten-free flour mix
2 cups gluten-free cream of mushroom soup
1 fried onion, thinly sliced

For fried onions:
1 medium onion, sliced thin
1/3 cup gluten-free flour mix
1/4 tsp. sea salt
1/4 cup vegetable oil

Combine the sliced onions and dry ingredients in a large bowl, tossing until totally coated with flour and salt. Meanwhile, heat the vegetable oil in a nonstick skillet on medium-high. Brown the onions in the hot oil, approximately 3-4 minutes per side. Place the browned onions on a paper-towel-lined baking sheet.

Preheat oven to 400' for the baking the casserole. If using fresh beans, boil in lightly salted water for 5 minutes, then rinse with cold water and drain. If using canned beans, rinse and set aside.

In a large saucepan, melt the butter and toss in sliced mushrooms and pepper. Stir over medium heat for 5 minutes, then add garlic and flour, stirring to coat. Cook and additional minute, then add the sour cream and soup and lower the heat to medium-low. Cook while the mixture thickens, approximately 5-8 minutes more. Remove from heat and stir in half of the fried onions and all of the drained beans. Pour mixture into a large casserole dish and bake for 10 minutes, or until bubble. Sprinkle the remaining onions on top and bake for an additional 5 minutes. Serve warm. Refrigerate any leftovers.