Over medium high heat (6.5 out of 10) heat up 2 tbsp olive oil in a large skillet.
Add fennel, sprinkle with 1 tbsp sugar and 3/4 tsp sea salt and start browning, stirring occasionally. Once fennel starts browning, reduce heat to medium low (4 out of 10). Cook until golden brown, about 15 minutes and put aside.
Cut chicken in 10 pieces, sprinkle with salt on both sides.
In large skillet over medium high heat (7 out of 10), add 2 tbsp olive oil and brown meat in batches. Do not overcrowd the meat, brown 3-4 pieces at the time. Transfer browned meat to a plate and put aside.
Add onions and cook until soft and translucent and then deglaze the bottom with white wine.
In the deglazed skillet with onions, add browned fennel, garlic, caperberries and 2 tbsp sugar, stir it all together.
Place browned chicken pieces on top of the vegetable bed in the skillet, add freshly ground pepper.
Pour in red wine vinegar and cook uncovered for 3 minutes, put the lid on.
Turn the heat down to medium low (2 out of 10) and cook on low simmer for 20 minutes.
Remove lid, increase heat to medium (5 out of 10) and cook for 6-7 minutes to thicken the sauce.
Remove from heat, cover and rest for 10-15 minutes. Serve warm over bed of pasta.