I am similarly obsessed - and they sell the dressing, which has a label of ingredients. I tried a batch, good, but not even close to how yummy theirs is...Here are the ingredients
lemon juice, champagne vinegar, evoo, shallot, salt and pepper
Its so good I'd buy it from them regularly, but alas. Not when they're 30 miles away! Let me know if you figure it out - I suggest buying a bottle next time your're there to taste test against. Good luck!