Bake fish fillets in 425F toaster oven for 15 min or convectional oven for 20-25 min at 425F.
Meanwhile, saute chopped onion in a small frying pan with butter on medium heat for 3 min or until soft. Remove from heat.
Then, make Sriracha Aioli Sauce. In a small bowl, add minced garlic and salt. Mash garlic with a spoon until it becomes a little pasty. Add mayonnaise, lemon juice, olive oil and Sriracha sauce. Mix until well combined.
When fillets are cooked and slightly cooled, put them in a bowl and mash them with a fork. Add mayonnaise, Djon mustard, bread crumbs, cooked onions, parsley, lemon juice, garlic powder and black pepper. Mix together until just combined. Don't overmix.
Form fish mixture into four equal sized patties. Return to toaster oven or oven for another 10 minutes to heat through. Top with a spoonful of Sriracha Aioli Sauce.