Fill a large bowl with cold water. Prepare a heavy cleaver and thick wooden cutting board to cut through meat and bones with ease.
Chop the chicken parts and submerge them into cold water to soak refrigerated for 6-8 hours.
Strain colored water.
Wash chicken pieces under running cold water.
Transfer clean chicken pieces into a stock pot and cover with cold water 4" on top. Place over high heat, cover with a lid to bring to boiling. Reduce heat to medium and skim the foamy skum. Turn the heat to medium-high to make it boiling again. Keep boiling for an hour.
Meanwhile, prepare aromatics. Peel ginger and slice it 1/4" thick. Peel garlic. Peel and quarter onion. Peel carrot and chop it to large pieces. Wash and prepare white ends of scallions.
Place a skillet with avocado oil over medium-high heat. When oil starts smoking, add onions, garlic, and ginger and caramelize them without burning.
After the first hour of cooking the stock, add caramelized vegetables and scallions. Continue boiling for another two hours.
After the first three hours of boiling, the stock becomes thick and creamy. Remove and discard scallions. Turn heat to high for rapid boiling for the last half an hour. This step will emulsify the chicken fat collected on the top.
Strain the stock and squeeze more from the chicken solids. To emulsify chicken fat even better, use a blender. Then refrigerate or freeze, portioned.