Where do the two of you live? I'd pick a place that doesn't require too much travel for any of you. I'd also give some thought to what sort of food your date likes, you don't want to take them to a chinese restaurant if they don't enjoy chinese dishes.
In Port-Louis, I'd say Grand Canton Restaurant (chinese) and Rozi Darbarr Restaurant (indian) are quite good: decent price, good food, not too crowded and giving you some level of privacy if you get a table for two.
Good luck :)