In a medium sized pan, heat oil until it begins to warm (on low heat). Once oil beings to warm, add in minced garlic cloves, diced serrano chili, 1/2 tsp hing, 1/2 tsp cumin, 1 tsp taco seasoning, chili powder and smoked paprika. Let the all ingredients come together until fragrant about ~30-60 seconds, mixing occasionally. Next add in diced onions, red bell pepper and mushrooms. Once again allow all ingredients to simmer together for several minutes on medium heat (about 5-6 minutes).
Next add in bread crumbs, ketchup, siracha sauce, red pepper flakes, 1/2 tsp cumin,1 tsp taco seasoning, dried parsley, garlic powder and salt and pepper to taste. You can taste test the mixture at this point. One more time, mix together so all ingredients are incorporated and then gently mash a couple more times. Form into 4 patties. (Patty tip: I like to start with four equal sized balls. Then place each ball on a flat surface and press down with the palm of your hand. This will create that round burger shape.)