Vegetables: Carefully remove 4 large lettuce leaves from the iceberg head and set aside. Slice 1 avocado and set aside. Finely slice 1 large onion and add to a small pot along with 1 tsp olive oil and 1 tsp butter. Bring the pot to medium heat and stir the onions occasionally while you prep the mince.
Mince: Add 200g beef mince to a bowl and season with 1/2 tsp salt, 1/2 tsp pepper, 1 tsp garlic powder and mix well. Portion into 4 balls. Heat a large pan to high heat and add 1 tsp canola oil. Place the balls on the pan and squish them out as flat as possible with a spatula. Let them cook for 2-3 minutes per side.
Finish off: Once the burger patties are nearly cooked, add 1 tsp brown sugar and a splash of water to the onions. Stir through until the sugar caramelises and the water evaporates.
Plate up: Carefully fold the lettuce leaves into burger sizes. Lay aioli, avocado, patties, and top with pickles and caramelised onions.