Cut the white fish fillets into bite-sized pieces. In a mixing bowl, combine flour (or cornstarch), salt, and black pepper. Coat each piece of fish in this mixture and set aside.

Heat butter and olive oil in a skillet over medium heat. Add the fish bites and cook for about 3-4 minutes on each side until golden brown.

Remove the fish from the skillet. In the remaining oil, sauté minced garlic for 30 seconds. Stir in lemon juice and zest, then return fish to pan for 1-2 minutes.

In a bowl, whisk together mayonnaise, minced garlic, lemon juice, and a pinch of salt until creamy. Adjust seasoning as desired.

Serve the fish bites on a platter garnished with parsley, alongside the garlic aioli for dipping.