I really like low-cooking time recipes for summer because my kitchen is not air-conditioned. So when I'm up in the wee hours, I boil water for pasta and stick it in the fridge.
I sometimes throw some frozen brocolli florettes right into the water that I'm using to boil the pasta (throw the broccoli in as soon as the water comes to a boil, then when the water comes back to a boil, toss in the macaroni and boil until the macaroni is done). I used to grow broccoli, and it works about the same. The timing is such that the veg is still green with a little crunch when the pasta is done. It also works with fresh or frozen green beans.
Couscous and taboule are my real summer go-tos because, once again, I can make them in the morning in very little time and eat them cold or nuked at supper time.
Both can be turned into entire meals. I use Near East brand because it is pretty readily available.
When you have great tomatoes in the summer, and basil, all you need is olive oil and garlic. Maybe a little hot pepper if your garden (or favorite market) supplies. I make tons of pesto in the summer, but rarely eat it then, just using the fresh basil and freezing the pesto. To me, pesto needs nothing but pasta. But I do use it to season lasagna in my tomato sauce during the winter (lasagna is NOT a summer dish for me!).
If you're into a meat-free meal once in awhile, a can of chick peas in your pasta are great.
For greens, spinach, swiss chard, and beet greens can be roughly chopped or julienned for the tougher ones, then tossed into the pasta at the last minute (drain pasta, put back on the pot on the burner with olive oil and seasonings for just a minute or two).
All can be topped just before eating with a strong, dry cheese: parmesan, romano, asiago, any of the blues, feta.