Three Recs for Fun/Trendy Restaurants for one at Bar
Visiting SF for work and will have at least 3 dinners to explore fun, inventive restaurants where a nice spot at the bar for one would be a great experience. Staying near Union Square, but within the central urban area would be fine (not just a few blocks from hotel). No need for any Asian or fusion experience, as home as plenty of that to offer, simply fun, festive places to watch the local crowd, not a tourist crowd. Price point can be simple mom & pop to upscale and pricey.
I doubt Goat Hill on monday is what the OP really wants. It's local, but it's overrun with families on Monday.
Most posts point out that outside the tasting menu joints, just about everywhere is good for solo diners. The areas overrun with tourists are the wharf, north beach, the embarcadero, union square, to a lesser extent the financial district. Among those areas there are the more and less touristy, but simply take a taxi out (say, to the Foreign Cinema, the slow club, Pakwan, ANYWHERE) and you'll be in the middle of locals.
Here's a locals-rec: