1Rinse the quinoa in a strainer under cold water until the water runs clear.
2Place the quinoa in a large saucepan, cover with about 2 to 3 inches of cold water, season with salt, and bring to a boil over medium-high heat. Reduce the heat to medium low and simmer, uncovered, until the white outer casings on the quinoa have popped, revealing translucent little beads, about 15 to 20 minutes.
3Strain the quinoa and transfer it to a large bowl. Let sit at room temperature until cooled, about 45 minutes. (Or to cool it faster, spread the drained quinoa in a single layer on a rimmed baking sheet; it’ll cool in about 15 minutes. Then transfer to a large bowl. You can prepare the recipe through this step the night before you make the salad.)
4Add the tomatoes, olives, measured lemon juice, and olive oil. Season with salt and pepper and stir to combine. If you choose, fold in the cheese. Taste and add more salt, pepper, or lemon juice as needed.