My mother taught me this wonderful recipe for summer using tomatoes and cucumbers (I don't have amounts, I always do it to taste):

Tomatoes, quartered, then each piece halved
Cucumbers, chopped into medium-sized (approx 1 to 1-1/2" square) pieces, or sliced.
Garlic powder and/or garlic salt
Dried or fresh oregano
Olive oil

Cut tomatoes and cucumbers and combine in a bowl. Sprinkle on garlic salt or garlic powder (or both) and oregano. Mix and let sit for about 15 minutes to let the flavors of the ingredients combine. Just before serving, drizzle on olive oil and mix. Enjoy!