Preheat oven to 375 F. Grease 9-inch pie plate with a little grapeseed oil.

To medium saucepan, add quinoa along with water or broth. Bring to a boil over medium-high heat, cover, reduce heat to medium-low, and cook until all the water has been absorbed, about 10 minutes. Fluff quinoa with fork and transfer to large bowl. You should have about 2 cups cooked quinoa. Set aside to cool for 5 minutes.

To bowl with cooled quinoa, add 1 egg and beat well with fork until well combined. Transfer quinoa mixture to prepared pie plate and evenly press into bottom and up the sides. Bake in preheated oven for 20 minutes. Press down crust with the back of a spoon to compact and avoid any leaks when pouring on the quiche filling. Set crust aside to cool for 15 minutes. Reduce oven temperature to 350 F.

While quinoa crust cools, make pepper relish. In medium bowl, stir together diced roasted red peppers, parsley, vinegar, red pepper flakes, and salt. Set aside to marinate, stirring occasionally, while making quiche filling.

In large frying pan, heat grapeseed oil over medium-high heat. Add green onions and sauté until tender, about 4 minutes. Add spinach and sauté until wilted and most of the excess liquid in the pan has evaporated, about another 2 minutes. Transfer spinach mixture to large bowl and add milk, cheese, nutmeg (if using), and remaining 3 eggs. Whisk until very well incorporated and pour into prepared crust. Bake until just set, about 35 minutes. Set aside to cool for 20 minutes.

When ready to serve, cut quiche into 6 wedges and transfer to serving plates. Spoon a dollop of pepper relish over top and serve immediately.