Finely chop the salmon fillet into small pieces, almost to the consistency of ground meat. Add it to a large bowl with the red onion, parsley, dill, 3 tablespoons of capers, lemon zest, chili flakes, salt and pepper. Mix to combine. Add the egg and panko breadcrumbs and mix to combine. The mixture should hold together lightly. If it is too crumbly, add some more breadcrumbs.
Shape the sliders into rounds about 2 centimetres thick by pressing the salmon mixture between your hands or using a ring mold or cookie cutter. Place the rounds on a lightly oiled plate and repeat the process for the remaining mixture. Refrigerate for at least one hour to let the sliders set.
In the meantime make the garlic aioli. Mix the mayonnaise, garlic, lemon juice, salt, and pepper in a bowl. Cover and refrigerate for at least 30 minutes before serving.
Heat a frying pan over medium heat and add 1 tablespoon of olive oil. Place 6 salmon sliders (or as many can fit in the pan without touching) into the pan and fry for 3 minutes. Flip and continue to cook for another 3-4 minutes or until golden brown and there is no bright pink colour left. Set aside on a serving plate for later. Repeat this process for the rest of the salmon sliders, adding 1 tablespoon of oil to the pan for each new batch.
Finally, prepare the fried capers. Add the 1/4 cup of olive oil to a small pan over medium-high heat. Add the capers and fry for 5-6 minutes, tossing often until the capers are crisp. Remove from the pan and drain on a paper towel.
Garnish each salmon slider with a dollop of garlic aioli, a few fried capers, and a fresh sprig of dill.
Serve warm or at room temperature. Enjoy!