Hooray! I've rediscovered an old love.... dijon mustard! This stuff is great. The brand I have (Safeway... I'm cheap) has zero calories and zero grams of fat, and LOTS of potential uses. I've used it as a marinade on chicken breasts, as a base for my first home-made vinaigrette, and just plain on sandwiches.
My problem with sandwiches is I tend to like the kind that go best with lots and lots of fatty mayo -- tuna salad, chicken salad, ham and swiss. But lately I've been trying different combos that taste just fine without mayo. I've got lowfat roast beef and lowfat pastrami, and they go great with this mustard. So I still get the convenience of just grabbing a sandwich, and getting the protein and dairy boost (cuz I'll still allow myself one slice of cheese), without the unnecessary added fat goo from mayo. Hooray!