As much as this city loves its lines, there are few waits in San Francisco worth it. Mama's: worth it. Flour + Water: worth it. Hong Kong Lounge: worth it, too. This Outer Richmond dim sum place has seen its ups and downs over the years, but it's definitely on a high upswing, hitting a peak when it comes to both variety and quality. Giant dragon boat packets of sticky rice studded with meats. Rice-noodle rolls with the consistency of tulip petals. Steamed spareribs that slip off the bone. Pastry puffs so fragile they shudder and shed when the table is bumped. And because the dim sum is ordered from a menu, it doesn't sit around on rolling carts, growing flabby. The Saturday-morning wait is an hour if you're lucky. Bring a newspaper and a thermos of coffee, and by the time you're done with the sports section the siu mai will be waiting for you.