First...keep it in the fridge. I'm a horder, and the beautiful crockery bottle of pistachio oil I bought in Paris in 2002 is still in there with a few drops left, and they don't taste rancid even now!
I think the stuff has an affinity for roasted beets.
Yes, vinaigrette, as it's not an oil to cook in. The link is a recipe for a pistachio-caper viniagrette dressing a fennel avocado mint salad. Brush on broiled or grilled fish, shrimp, or grilled bread or drizzle a little on your next pot of saffron risotto.
To a warm lb. of cooked whole wheat noodles, I toss in dry roasted pistachio nuts and a healthy drizzle of pistachio oil and a few ounces of grilled chicken or salmon and the juice from 1/2 a lemon and call it dinner.