Prepare the Vinaigrette: In a medium bowl, combine red wine vinegar, Dijon mustard, finely diced shallot, sea salt, black pepper, and pure maple syrup (optional). Gradually whisk in olive oil until the dressing is well combined and emulsified. Set aside.

Dress the Spinach and Apples: In a large serving bowl, add the prewashed spinach. Pour the shallot vinaigrette over the spinach and toss gently to coat. Add the thinly sliced Fuji and Granny Smith apples, and lightly toss again to distribute a bit of the dressing onto the apples.

Roast the Pistachios (Optional): If using roasted pistachios, preheat your oven to 350°F (175°C). Spread the pistachios on a baking sheet and roast for 6-8 minutes, or until golden brown and fragrant. Allow them to cool slightly before chopping them into smaller pieces.

Assemble and Serve: Divide the dressed spinach and apples among four individual serving bowls, or arrange them in a large serving bowl. Sprinkle the chopped pistachios, dried cranberries (or cherries), and crumbled blue cheese over the salads. Serve immediately.