I’ve ordered Old Fashions at a few places and they’re usually terrible. Cause, usually it’s like a fruit smoothie in there. You wonder what…[the bartenders] were thinking when they made it.
Here, here. And Mr. Gruber (around ~1:59:00):
I’ll give you my Old Fashioned recipe…two small dashes of [Fee Brothers] orange bitters,… two small dashes of their regular bitters – their Angostura bitters…[one] demerara sugar cube, little bit of water just a little bit, just enough to get the sugar cube dissolved…muddle that up, get that sugar cube as dissolved as you can get it put a whole bunch of big fistful of cracked ice in there. Two ounces of bourbon, stir that thing for as long as you can bear to stir it…strain it, put it in a glass with one big-ass ice cube and then orange peel, lemon peel, whatever you’ve got in the house.
They also mentioned this website as a good, simple reference to getting started.