Healthy or unhealthy, depending on what sort of ingredients you use. I don't think these are anything special, but they're a lot better than what I had at a local kosher restaurant.  When I order a quesadilla (entree) for $6, I don't want to get a plain white tortilla with some greasy cheese melted on top, thanks.

Anyway, I used:
"whole wheat" (though I doubt they were 100% whole wheat) tortillas about the size of my hand (from tip of my pinkie to the tip of my thumb)
canned black beans
jarred salsa
mozzarella cheese

Mash the beans, adding enough salsa to make the mixture clump together a bit. Don't entirely smoosh the beans, just mush them a little to make a coherent glop of stuff.
Heat up an ungreased frying pan. I've had success with Teflon and aluminum, and will try it in a cast iron skillet when I have a big enough one handy.

Lay a tortilla on the hot frying pan. Spread a layer of bean stuff on it--maybe 1 cm thick? Leave a little room around the edges so the filling doesn't spill out.
Spread a thin layer of salsa over the beans.
Sprinkle cheese over the salsa.
Lay a second tortilla over the whole thing, press slightly with a spatula, and wait for the bottom to get crispy. Flip, cook on other side until the cheese is melted and the tortilla is crispy. If the tortilla isn't crisp, it won't taste very good.

Put on plate, cut in quarters or smaller wedges, and serve with sour cream.

*Whole wheat really doesn't seem to make a difference in terms of taste or function, here, so it seems like a good choice. Usually I don't use whole wheat tortillas since they don't seem as pliable.