In a small bowl, whisk together the olive oil, red wine vinegar, Dijon mustard, and honey until emulsified and well combined. Season with kosher salt and freshly ground black pepper. Set aside at room temperature. I like to make my dressing while the proteins are still warm from cooking—the warmth helps the flavors meld together beautifully.
Place the baby spinach in a large serving bowl or on individual plates. Arrange the cooked quinoa and cooked chicken evenly over the spinach, creating a balanced distribution of protein and grains throughout.
Top the salad with the blueberries, feta cheese crumbles, and toasted sliced almonds. For the best presentation and texture, I scatter these ingredients evenly across the top rather than tossing them in—this keeps the almonds crispy and lets each bite deliver different flavors and textures.
Drizzle the vinaigrette from Step 1 over the salad and toss gently but thoroughly to coat all ingredients evenly, ensuring the greens are well dressed while maintaining the structure of the quinoa, chicken, and toppings. Serve immediately while the spinach is cool and crisp.