Heat oil in pot, stir scallions and garlic, cover, cook 5 minutes.
Stir in favas, add water to cover by 1 inch.
Cover, bring to a boil, reduce, simmer 10 minutes.
Trim and peel chokes, keeping 1 inch stem, then scrape out the chokes.
Put chokes in pot with the favas stem side up. Salt.
Cover, simmer until chokes are very soft, 30-60 minutes.
Whisk flour and lemon juice, add ½ cup hot pot juices, then return to pot, and
stir.
Simmer low heat until thick, 15-20 minutes. Add parsley and serve.