Somsak Pu Ob has grown from a small street cart to several locations across the city, but the original street vendor, who still sets up along Charoen Rat Road, is the best.
Their signature dish is pu ob woonsen, a simple amalgamation of meaty crab lightly fried with pork fat and baked with glass noodles, black pepper, coriander root and soy sauce. A garnish of crunchy spring onions is tossed in before serving. The glass noodles soak up the flavours and arrive slightly sticky without being wet while the crab is sweet and shells already cracked so minimal prying is needed. Don't even think of not eating it without the seafood sauce, a lively blend of green chillis, garlic, fish sauce and lime juice.
You can find it sold across Bangkok, but the uncompromising quality of the ingredients make Somsak Pu Ob the best in the city, if not the country.
It's a basic arrangement here - just a large metal pushcart covered with baskets of produce, a prep station stacked with small metal woks and a few gas canisters feeding burners set next to a collection of pavement tables. It's popular, very popular. If you don't want to wait for a table, try to visit outside peak dining hours. They set up shop at 5pm each evening (other than Mondays) and close at 10pm or whenever they sell out.
The owner chef here cooks just four woks at any one time, so be prepared to wait a little longer than most street food.
The baked crab and noodles are a little more expensive than others in the city, but the quality seafood is well worth the extra spend. Prices start from 300 THB for crab (around US $10).