For the salad:
250g cups quinoa
700ml water
1/2 tsp kosher salt
1 large English cucumber
340g roasted red peppers
1/2 small red onion
1 cup pitted olives
15g coarsely chopped fresh parsley leaves
115g feta cheese
For the dressing:
3 tbsp olive oil
2 tbsp red wine vinegar
1/2 tsp dried oregano
1/2 tsp kosher salt, plus more as needed
1/4 tsp freshly ground black pepper
Place quinoa in a fine-mesh strainer and rinse well. Place the quinoa, water, and 1/2 tsp kosher salt in a medium saucepan and bring to a boil over high heat. Reduce the heat to low, cover, and simmer until the quinoa is tender and all the liquid is absorbed, about 15 minutes. Uncover and fluff with a fork. Transfer the quinoa to a rimmed baking sheet, spread into an even layer, and refrigerate until cooled completely, 10 to 15 minutes.
Place all the dressing ingredients in a small bowl and whisk to combine.
Chop 1 large English cucumber into rough 1/2-inch pieces, drain and coarsely chop roasted red peppers, coarsely chop 1 cup pitted olives, finely dice the red onion. Add everything to the bowl.
Add the cooled quinoa and toss to combine and evenly coat in the dressing.
Coarsely chop parsley leaves and add to the bowl. Crumble feta cheese into the salad and toss again gently to combine. Serve at room temperature or chilled.