I am prone to buying ten pound bags of oranges this time of year. I think it's a primal urge to ward off scurvy.
Cut the ends and peel off of five oranges. Cut into slices, and then bite-sized cubes. Add 1/4 onion, minced and 1 handful cilantro, chopped. (Fair warning: I made this salsa to suck up to a toddler with a love of chips. It's super mild. And maybe a little bit acid for small people.) Add 1 tsp. sugar and 1/4 tsp salt. Just before serving, add 2 avocados, chopped coarsely. Stir.
I suppose you could add more onion, a couple of peppers, and maybe a dash of lime. Taste it first though, because the acidity can be a little intense.