In a large bowl, add quinoa, farro, barley, cucumbers, tomatoes, radishes and cotija cheese. Stir together and set aside.
For the dressing: in a small bowl, add olive oil, white wine vinegar, dried oregano, cilantro, sea salt, black pepper and lime juice. Whisk until combined.
Pour the dressing onto the mixed salad and stir to combine. Cover and refrigerate for 15 minutes until chilled, or enjoy immediately.