For summer, I try to turn on my oven as little as possible and I like dishes that can be served cold/room temp or things that are good with a cold beer. I also associate anything grilled with summertime — foods like corn on the cob, grilled veggies, portobello burgers, etc. — and lots of fresh fruit salads and raw sliced veggies with hummus for snacking. Also a great time to experiment with salads.
I like pasta salad with tons of finely chopped vegggies (cucumber, bell pepper, cherry tomatoes, red onion, olives), garbanzo beans, and Italian dressing (either store bought or a simple EVOO/red wine vinegar dressing with some powdered garlic & spices mixed in).
Whole grain salads — similar idea as above, but there are endless variations with quinoa/bulgur/wheat berries as the main grain and then whatever good veggies you have on hand (raw chopped veggies are always good, but you can also use pre-coooked veggies like marinated roasted peppers, artichoke hearts, hearts of palm, or roast a pan of sweet potatoes and carrots in advance to toss in) and a light dressing or marinade. Throw in some canned beans/frozen peas or a cheese or meat to make it a satisfying one-dish meal.
Caprese – just basil, tomato, and cheese. I don’t eat cheese anymore so I sometimes make avocado-tomato-basil salads instead and find them to be quite satisfying and delicious.
Veggie fajitas or tacos – grill some vegetables (you can use a broiler or a stove top grill if you don’t have an outdoor one), sautee a can of pinto or black beans with some EVOO, fresh garlic, cumin, oregano, chili powder, any other desired seasonings, heat some tortillas on a grill or in the oven, and top with salsa (fresh or jarred), avocado, cilantro, green onions, & cheese/sour cream if desired. Endless variations here (Spanish rice, roasted veggies, potatoes, corn, meats, etc.) and I always find Mexican to be good summer food.
Potato salad – For a lighter one, you can use an EVOO/red wine vinegar dressing instead of the typical mayo one. Also use fresh herbs like dill for more flavor. I personally love this recipe for jalapeno-dill potato salad and have gotten rave reviews at potlucks (just use regular mayo if you’re not vegan): http://lesliedurso.com/2014/07/jalapeno-dill-potato-salad/
Salads — summer is a great time to make a meal out of a big salad. Just stock the fridge with whatever you like on salad – I love mixed greens, garbanzos, cucumber, cherry tomatoes, sprouts, avocado, sunflower seeds, and Goddess dressing, so I try to keep ingredients like that on hand so there’s something easy to throw together for dinners/lunches.
Tartines – for a light lunch, a tartine (open-faced sandwich) with a side salad is a good option. Along the same lines, bruschetta is a great summer appetizer, which can turn into a light meal served with a salad with some protein in it.