Nut oils like pistachio, macadamia, walnut, pecan, etc., are best as finishing oils. With their robust flavors, just a dash of these flavor enhancers will suffice. Please do not deep fry or sauté with these oils; with their low smoking points, the taste of your food will become bitter. I suggest not adding these oils to salads since the flavors can be intense, some can be used for salad dressings, but you would want to use sparingly. Folks with nut allergies should avoid these oils at all costs.
Chef, how would you use these oils?
I suggest making heavy, hearty dishes with the essence of wild game, mushrooms, and cream bases, in desserts, and so on. Ever try chocolate ice cream with pistachio oil? How about hazelnut? Just a drizzle, maybe a little sea salt. Remember, just a hint is needed. With their intense flavors, I don't recommend these finishing oils with delicate ingredients like eggs, lighter fish, or soft tofu! Infused oils are expensive and usually come in smaller bottle formats.
Are there nut oils available for deep frying?
Yes, peanut oil, with its high smoking point, is best for deep frying. At the same time, refined peanut oil is a little lighter and doesn't absorb in other foods. You will find peanut cooking oils in a lot of Asian cooking.
Side note:
What about sesame oil? How is this oil best used?
Sesame is best as a marinade, with salad dressings, or as a finishing oil.
If you have food allergies, politely ask which products the host used in the recipe. Instead of asking for "the recipe," the recited ingredients could forewarn you of an oncoming allergic reaction.