My family eats a lot of stir fries and sesame oil is a critical ingredient in many of them. Unfortunately, my wife is allergic to sesame so we need an alternative. Has anyone had success recreating the sesame oil flavor with a non-sesame-based food?
Sesame oil has such a distinctive flavour, I'm afraid there's nothing that will give you exactly the same taste. Many sites suggest peanut oil, but this is more or less tasteless in my experience.
I would suggest toasting some unsalted peanuts or cashews and adding them to the stir fry, to get that roasted, slightly smoky flavour. Just add them to a warm, dry pan and toss frequently to prevent burning.
If you're feeling really adventurous you might even try smoking some peanuts (you can do this in a wok with certain wood chips and a bamboo steamer, plenty of instructions online).
You can simply omit the sesame oil, and most recipes should work just fine. The sesame flavor is pleasant but not required.
You might also consider substituting a nut oil such as walnut oil for some of the rich flavor of sesame oil. Drizzle it on at the end of cooking, and stir it in.
I recommend roasted pumpkin seed oil, which has a number of similar qualities, but tends to be expensive and may require refrigeration after opening.
I have this issue, as my son is very allergic to sesame, and also to peanuts and basically all tree nuts (precluding the nut-based suggestions above). When I make fried rice I like to use chopped-up pancetta at the appropriate point in the recipe (give it enough time to render much of its fat). No, it's not a match, but it seems to fill a somewhat comparable role in the flavor, perhaps because of the smokiness. You could probably substitute bacon if you lack pancetta.
Maybe it would help to use a few drops of liquid smoke as well.