Bring 1lb chicken feet and 2lb pork neck bones in 4 liters of water to a boil in a wok.
Reduce to a simmer and skim off grey foam every few minutes until none remains, 20ish minutes.
Add 2 whole green onions, cut into largish chunks, and optionally 1tbsp black peppercorns.
Cover; reduce to bare simmer and allow stock to be extracted slowly, at least 90 minutes but up to 2 1/2. The goal (admittedly tough to know with a full wok without experience) is to end up with 2 liters of stock post-extraction; in my wok, that means losing approx. 2" of liquid in a full wok before straining, to end up halving the liquid volume.
Strain stock, cool and store.
To make this into a fast soup: bring veg and root vegetables (carrot and green onion whites is good) and optionally precooked shredded chicken to a simmer in a liter of stock. Simmer til root vegetables are softened. You can add greens (bok choy etc) and precooked rice or wheat noodles, or fresh rice noodles, towards the end of cooking.
Add salt and top with a fresh herb (cilantro/parsley/dill).