Preheat oven to 350 degrees F (176 C) and add raw hazelnuts to a parchment-lined baking sheet.
Once oven is preheated, toast hazelnuts for 7 minutes. Then remove from oven and add remaining ingredients directly to the hazelnuts (oil, coconut sugar, maple syrup, sea salt, and cinnamon). Use a spatula to thoroughly toss/combine.
Place back in oven and roast for another 4-6 minutes or until fragrant and golden brown. Set aside to cool.
In the meantime, prepare dressing by adding all ingredients to a jar (or mixing bowl) and shaking vigorously (or whisking) to combine. Taste and adjust flavor as needed, adding more balsamic for acidity, maple syrup for sweetness, salt or pepper for flavor balance, or olive oil for creaminess. Set aside.
To serve, add spinach, half of the strawberries, and half of the roasted hazelnuts to a large mixing/serving bowl. Drizzle with half of the dressing and toss to combine.
Plate and garnish with the vegan feta (optional) and remaining strawberries and hazelnuts, and serve with remaining dressing (if you like a more heavily dressed salad).
Best when fresh, though leftovers store separately in the refrigerator up to 3 days. Store hazelnuts well sealed at room temperature.
*Nutrition information is a rough estimate calculated with olive oil and without optional ingredients.