1
Using a microplane or the fine side of a box grater, grate the garlic cloves. Combine grated garlic, olive oil, lemon juice, chilli flakes, salt and pepper. Coat each side of the fish steaks well with this mixture. Refrigerate for at least half and hour.
2
Set a skillet over medium high heat and, once hot, add just enough vegetable oil to coat the bottom. Place the fillets, two at a time depending on the size of the skillet, skin side down and cook for four minutes. Flip and finish cooking on the other side for another three to four minutes or opaque throughout. Remove to a paper towel.
3
To arrange the burgers, place a handful of baby lettuces on the bottom half of a burger bun. Top with one fish steak, a generous dollop of the avocado sauce, and the top half of the bun.