Rinse 1 cup of quinoa under cold water in a fine-mesh strainer for about 1 minute until the water runs clear.

Combine rinsed quinoa with 2 cups of water and a pinch of salt in a medium saucepan. Bring to a boil, reduce heat, cover, and simmer for about 15 minutes.

Remove saucepan from heat and let sit for 5 minutes with the lid on, then fluff quinoa and spread out to cool on a large baking sheet.

In a large mixing bowl, combine cooled quinoa, 1 cup of dried cranberries, 1 cup of chopped walnuts, 1/2 finely diced red onion, and 1/4 cup chopped parsley. Add feta cheese if using.

In a small bowl, whisk together 1/4 cup of olive oil, 3 tablespoons of apple cider vinegar, and a pinch of salt and pepper until well-emulsified.

Pour the dressing over the quinoa salad mixture and gently toss with a spatula until well coated.

Cover the bowl and refrigerate for at least 30 minutes before serving.

Give the salad a final toss, taste for seasoning, and serve chilled or at room temperature.