Heat oil in a 3-4 quart saucepan over moderate heat.
Add onion and garlic, cook, stirring, until golden ( 8 mins)
Stir in remaining ingredients ( except pork, buns, and coleslaw)
bring to simmer, cover, and cook for 5-10 mins
Add pork, cover, and simmer, turning occasionally until tender
(about 45 minutes)
Pull pork apart in pan with forks or other handy kitchen tool
continue to cook just enough to distribute sauce and keep hot
Divide pork among bottoms of buns and top with some lemon
coleslaw