Finely dice peeled onion. Season chicken fillet with salt and pepper, fry in 2 tbsp. hot oil on both sides. Place in an ovenproof dish and roast in a heated oven at 200 degrees on the 2nd rack from the bottom for 15 minutes. Add onion and 1 tbsp. oil to the meat roast form, add 2 tbsp. curry, sweat briefly. Extinguish with orange juice, bring to a boil, then cool.
Remove peel from mango, cut flesh from stone and into narrow wedges. Season with 2 tbsp lime juice, slaz and pepper. Cut avodacos in half, remove stone, remove halves whole from peel with a spoon and cut into fans, brush on the spot with 2 tbsp lime juice and sprinkle with a little salt and pepper.
Finely chop chervil except for a few leaves, stir through with curry mixture, sour cream or crème fraiche and mayo. Season with pepper, sugar, salt, 1 tbsp. lime juice. Cut meat into thin slices, arrange with mango, avocados and sauce. Serve sprinkled with crushed red pepper and chervil.