These are the types of hands that make you or break you in tournaments and it's said over and over that sometimes you have to gamboool. with that said...
preflop... i have absolutely no problem. 3.5 to 1 on your money to call on the button with low suited cards is a makable call with an M of 14. Min raising was a terrible play I feel by him in the blinds. It prices everyone back in and if he is holding AA/KK/AKs he is just building a pot for a player much like yourself to call with low suited connectors or pretty much any 2 cards in an unraised pot thus far (like your case, on the button)
The flop is huge for you, and about as good a flop as you might expect to see with 2d7d.
Now we have his continuation bet... 300 into a pot of 1000 and the other 2 limpers fold, I say you have to raise here and define your hand. You didn't say how tight or loose this guy had been playing, but I'm assuming min raise from the small blind his range is looking like JJ+, AKs/o, AQs/o. Maybe... just maybe some kind of suited connectors... there are already 3 limpers, so by min raising here in the small blind, he can be fairly certain noone is going to limp raise him and he can build a pot to take if the flop hits him hard.
Now that we have an idea of what he is holding (we can be certain this is a continuation bet or possibly trying to bet and give himself good odds to draw at) I would put him on a high ace or pocket pair. If he's holding a pocket pair, I'd assume it's gonna be bigger than 9's just for the simple fact that raising in the sb with a low pocket pair if going to put you in terrible position on the flop with 3 limpers. Thus, we can be certain that we're ahead and put in a good raise to define our own hand. We can also be sure that by raising here... he can only call us with an overpair or flush draw depending on the odds. An Overpair will likely pay you off no matter what you bet on that board, so your bet must be one that gives the wrong odds for a flush draw.
You moved all in for 3500 more... since you have him covered that math comes to... 1400 to win 3000. He has 9 outs to his flush on the turn and river (around 4:1 on both streets making it about 2:1) his call call is about 2.1:1. thus making his call +ev, although only slightly.
I hope all my math is correct, if not corrections would be greatly appreciated but it all looks good to me. In closing, this hand is a virtual conflip after the flop (remember he doesn't know his 7d isn't an out) so his call, because he is short stacked makes it a makable call. Don't blame yourself for being in the hand, you had position and good odds to call, and don't second guess your play on the flop, try not to be results oriented. His most likely holdings here are High ace or pocket pair. if you call his 300 bet, you still can't reason out a flush draw and when the 3rd club hits you have an even harder call. Make it as expensive as you can with that board so AK/AQ will be laid down, you will get pair off by a higher pocket pair, and flush draws will not be priced in. Unlucky for you that he had less chips and ended up just being priced in to call.
I say you make that same play with that board... 1/10 you get busted by a flush, 7/10 he lays his hand down and 2/10 you get paid off by a higher pair... one of those times he rivers his set if you're playing on stars
