Make the lemon vinaigrette by combining lemon juice, olive oil, minced garlic, sea salt, and freshly cracked pepper, to taste.
Whisk until well combined. Set aside to allow flavors to mingle.
Side Note: We like our vinaigrette tangy, if you don't, add more olive oil, to taste.
Combine the arugula with spinach in a large bowl. Add the thinly sliced red onion and toasted pine nuts.
Whisk the lemon vinaigrette well then drizzle some on top of the salad, to taste. Toss to coat the salad evenly.
Place on serving plates then top with shaved Parmesan and freshly cracked black pepper, to taste.
Serve and enjoy!