It would probably depend on what type of food (the other person) enjoys. Once I know what that is then I would think about the restaurants I've been to that specialize in that type of food. If it is someting I never go for then I'd do some google searches to see which restaurants in my area are rated the best for that type of food.
One example for me personally is sushi. I don't eat it but if the other person loved it I would try to find a restaurant in my area that was known for being one of the best!