In a medium pot, heat olive oil over medium heat. Sauté diced onion for about 5 minutes until soft and caramelized. Add quinoa and toast for 2 minutes. Pour in water, apple cider vinegar, lemon juice, salt, and pepper. Bring to a boil, cover and simmer for 12-15 minutes until quinoa absorbs water.

Chop vegetables and fruits while quinoa cooks: slice green onions, chop nectarines, cut cucumber into cubes, remove corn kernels, halve the tomatoes. Set aside in a large mixing bowl.

Once the quinoa is cooked, let it cool for about 5 minutes. In the bowl, mix chopped ingredients with a pinch of salt and pepper. Fold in warm quinoa carefully.

Taste and adjust seasoning as needed. Add more salt, pepper, or lemon juice. If desired, add sugar for sweetness. Mix gently and serve.