This works as either a cold salad or as a hot side dish (add some chickpeas either way, to make it a main-course in itself). It is both very easy to make, and very quick. As you can imagine, the lemon and mint flavours conjure the mediterranean climate, so let that be your guide for choosing something to serve with it - a nice Greek salad, perhaps, or some falafel patties, or perhaps a braised lamb shank or a merguez tagine. Its low effort requirement make it perfect for either summer nights when you don't feel much like cooking (or turning on the stove), or as a last-minute way to round out a bit of leftover stew that seemed smaller than you remembered when you pulled it out of the freezer.
I recommend using any bell pepper except green, here. The red, orange, and yellow peppers are much sweeter, and complement the flavours of the mint and lemon. The green bell pepper would impart a more bitter, vegetal flavour - not necessarily a disaster, of course, but less harmonious for the dish overall.
Couscous with Lemon & Mint