Begin by rinsing the farro thoroughly using a fine mesh strainer, then drain well. Place the rinsed farro into a saucepan along with 3 cups of vegetable stock. Bring it to a gentle simmer and cook uncovered for 25 to 30 minutes, until tender yet pleasantly chewy. Once cooked, drain any excess liquid and spread the farro onto a plate or shallow tray to cool evenly.

Repeat the same rinsing process with the quinoa. Add the rinsed quinoa to a pot with 1 cup of water. Bring to a boil, then reduce to a gentle simmer, cover with a lid, and cook for 15 minutes. Once done, fluff with a fork to separate the grains and allow it to cool by spreading it out onto a plate.

While the grains are cooling, prepare the vinaigrette. In a small mixing bowl, whisk together olive oil, lemon juice, red wine vinegar, Dijon mustard, shallot, oregano, salt, and pepper until well emulsified. Set aside to allow the flavors to meld.

Dice the cucumber, roasted red peppers, red onion, and sun-dried tomatoes. Add them to a large mixing bowl along with the chopped parsley, chopped cilantro, and crumbled feta cheese. Once the farro and quinoa have cooled, fold them into the vegetable mixture. Pour the vinaigrette over the mixture and toss gently until everything is well coated. Refrigerate the salad until ready to serve.

Preheat the oven to 450°F. Season the salmon fillets with salt and black pepper on both sides. Arrange the fillets skin-side down on a nonstick baking sheet or one lined with aluminum foil for easy cleanup. Bake in the preheated oven for 12 to 15 minutes, or until the salmon is cooked through and flakes easily with a fork. The flesh should be opaque and slightly golden around the edges.

Serve the warm, tender salmon alongside the vibrant grain and vegetable salad for a balanced, flavorful meal that brings both nourishment and freshness to the plate.