first, you definitely reacted correctly to your opponent's potion buy, although my opinion is that this buy was a mistake, thief or no. so "what's the ideal strategy for this board" is different from "what should i have done" since "what should i have done" depends on what your opponent does.
anyway, the question "what is the ideal strategy for this board" is interesting.
greatexpectations strategy is much more fun than this and might beat it; you'll have to ask a simulator, but here's what i'd do. before reading this, you should read the following fantastic article on the main site:
http://dominionstrategy.com/2012/01/09/combo-of-the-day-27-hunting-partyx/looking at the board, i don't see any red flag attack cards. i see hunting party, so i look for a terminal with plans to play hunting party/x. there are four: merchant ship, chancellor, thief, duchess. whenever i hit five i'm going to want to buy a hunting party, so merchant ship is out. thief i don't even actually see (again, it's a clever counter to P-stone and you did the right thing, but assuming the opponent doesn't go P-stone i don't want thief in my hunting party/x engine). duchess causes the hunting party reshuffle catastrophe. so my terminal will be chancellor. chancellor is a good terminal for hunting party, since chancellor actively corrects the HPRC, so i can even afford to pick up a worker's village for the +buy on a hand with 4 at some point (and maybe to play a merchant ship if for some reason i wind up picking one up). so i say "ok, hunting party stack + chancellor." normally i execute this strategy by getting at least 2 or 3 hunting parties before the first gold; not sure the optimal way.
then you have to ask "what obstructions are there to my strategy?" Usually with HP it's "my opponent will play the exact same strategy and i want more hunting parties first," something that's solved by tactics, not by strategy.
but in this case there's embargo, which really gets in the way. I can see 3.5 ways of dealing with it:
1. i can give up on hunting party/x and focus on another strategy. In this case, the only other convincing strategy is probably big money with a few merchant ships. no fun. If I do this, I am going to have to pick up an embargo myself, and embargo the hunting parties, or my opponent will roll me with the strategy I wanted to do in the first place. But if I do that, I want to do it ASAP, before my opponent has three hunting parties, so I probably have to open embargo. But if I do THAT, my opponent can just play the same big money strategy without sacrificing tempo by buying an embargo of his own. So I probably wouldn't do this.
2a. i can play hunting party/x and hope my opponent doesn't embargo the hunting parties. if he does, i can switch away to the big money strategy, secure in the knowledge that he's wasted some tempo in building the same big money strategy by buying an embargo, plus i have maybe one or two hunting parties in my deck that he doesn't have - seems like a good deal. This is probably what I would do.
2b. I can play hunting party/x and suck up the curses. I think this is a mistake, but I'm not sure. Hunting party is quite good at dealing with curses, and if you have a critical mass of them, those curses really don't matter, so this may be better than 2a, but i would do 2a.
3. i can play hunting party/x and embargo the embargoes. This I think is a mistake, as the opponent may be able to pick up an embargo before I embargo the embargoes, or he can just ignore the embargo on the embargoes and buy his own hunting party.
