Mix 2 tablespoons ground flaxseed with 6 tablespoons warm water in a small bowl and set aside for 10 minutes to make flax eggs.
Rinse beans and mash with a potato masher or your hands and add them to a large bowl. Puree veggies in a food processor, then add sunflower seeds, blend again and add mix to the bowl.
Next add the flax eggs, gluten free oats, quinoa flour, and almond meal and mix well. Add seasonings and taste. Add more seasonings if needed, it will depend on if you seasoned your veggies when you cooked them, it should taste flavorful.
Once you get the taste you like, allow mixture to set a while so oats soak in some liquid (you can also do this after you shape into patties). This will help with the texture of the burgers, the more you allow the oats to soak, they less mushy texture you will get.
In the meantime, wash and slice your stuffing veggies. Saute onion and mushrooms in medium pan with oil or veggie broth until cooked throughout and all water is released. Remove from heat and add peppers. Taste and add salt and pepper if needed, will depend on how your jarred peppers were seasoned.
Shape burger mixture into 4 inch patties and make a hole in the middle. Add some stuffing to the hole, then cover it back up. Cook in medium pan on stove top over medium heat for 6-8 minutes on each side (depending on stove).
Make sure to keep pan covered to help the burger cook throughout and achieve the best texture possible. This helps prevent a mushy burger. Check every few minutes to prevent burning, should be slightly browned when ready.
Allow the burgers to cool a bit to further help set them into a non mushy consistency, then serve on lettuce for a lower carb meal or on sprouted wheat or gluten free buns. Add toppings of choice. You can also serve with oven fries