Add the crab meat, spring onion, mayonnaise, sweet chili sauce and breadcrumbs and stir well.
Season, then cover and refrigerate for 30 minutes.
To make the avocado salsa, combine all the ingredients in a bowl, season with kosher sea salt and fresh ground black pepper, and toss gently to combine.
Using wet hands, form the crab mixture into 20 small flat cakes.
Heat about 1 1/4 inches oil in a large heavy-based pan and cook the crab cakes over medium heat for about 3 minutes each side, or until golden brown on both sides.
Drain well on paper towels or brown paper, and serve immediately, with avocado salsa to spoon onto the top.
NOTE: In America, what we term as the Spring onion has a slightly more and defined bulb and is typically larger than the slender and more delicate green onion (scallion). The flavor has more bite and is somewhat hotter.
IN ADVANCE: the crab mixture can be made a day ahead, then covered and refrigerated. Prepare the salsa close to serving time.