Combine the water and quinoa in a medium sized pot and bring to a boil. Reduce heat to simmer and let cook for about 15 minutes, or until the quinoa has absorbed all of the water. Fluff with a fork and set aside to cool.
In a large bowl, combine the sliced tomatoes, olives and cucumber. Add quinoa and spices and mix well. Drizzle olive oil and lemon juice on top and add feta cheese.
Toss everything together. Serve immediately or store in the fridge until serving.