I've gotten into the habit of keeping bean or lentil salads in the fridge at all times, because they're easy to make and really handy to have around. I make a big pot of beans, use about 2/3 in a salad and reserve the remaining 1/3 for use in other recipes. I generally use the same "recipe" for any bean salad, which involves soaking some diced onion in a shallow pool of apple cider vinegar, adding a chopped bell pepper, then tossing in some olive or hempseed oil, sea salt, herbs of choice, maybe some celery, and finally the beans. Switching up the beans and the herbs allows for some variety so it doesn't get too boring eating bean salad all the time.
For my black bean salad I soaked some diced onion in the vinegar for about 10 minutes, added some orange bell pepper, poured in some olive and hempseed oils, and then sprinkled in some cayenne, sea salt and a couple teaspoons of cumin powder. Then I tossed in the black beans (about 4 cups) and a couple handfuls of chopped cilantro.
I was concerned that the Mexican flavors might go weirdly with the apple cider vinegar, but it tasted alright to me. You could always just use lemon juice instead, I just didn't because I use lots of lemons in other foods and am trying to use more apple cider vinegar in my cooking.
As for the cilantro, I find that it's one of the few relatively affordable herbs available at this time of year, provided you buy a gigantic bundle. I used about a quarter of my cilantro in this recipe, and the rest I'll be using to make cilantro pesto with almonds, basically the basil cilantro pesto from Veganomicon without the pricey basil.