Lightly dust skin-side of sardines in seasoned flour, shaking off excess. Heat 20ml oil in a large frying pan over high heat, add half the sardines, skin-side down, cook until crisp (2-3 minutes), turn and cook for 30 seconds. Place carefully in a deep-sided non-reactive tray in a single layer, set aside. Wipe pan clean with absorbent paper, repeat with remaining sardines and oil.
Meanwhile, slice half the onion into thin rings and set aside. Coarsely chop remaining onion and combine with 300ml vinegar, garlic and paprika in a small saucepan over medium heat, bring to the boil, pour over sardines and set aside to marinate (10-15 minutes).
Meanwhile, blanch asparagus (1-2 minutes), then refresh, drain and halve lengthways. Combine in a bowl with onion rings, orange and parsley. Whisk remaining vinegar and extra-virgin olive oil in a bowl to combine, toss through salad, season to taste.
To serve, remove sardines from marinade with a slotted spoon, drizzle over a little marinade, and serve with salad.
This recipe is from the October 2009 issue of Australian Gourmet Traveller.