Mix the oats, quinoa, and millet in a fine mesh strainer and rinse for about a minute under running water. Set aside.
Heat 1 tablespoon olive oil in a 3-quart saucepan over medium-high heat. Add the rinsed grains and cook for 2 to 3 minutes or until they begin smelling toasted. Pour in 4 1/2 cups water and stir in 3/4 teaspoon salt, the ginger coins, and the zest of 1 lemon.
Bring to boil, cover, turn down the heat, and simmer for 20 minutes. Turn off the heat and let sit for 5 minutes, then remove the lid and fluff with a fork. Remove the ginger. Spread hot grains on a large baking sheet and let cool for at least half an hour.
Spoon the cooled grains into a large bowl. Stir in the zest of the second lemon.
In a medium bowl whisk the remaining 2 tablespoons olive oil with the juice of both lemons until emulsified. Whisk in the maple syrup, yogurt, and nutmeg. Pour this into the grains and stir until well-coated. Stir in the toasted hazelnuts and blueberries. Taste and season with additional salt, if necessary.
Refrigerate overnight; the flavors of this really come together overnight in the fridge.
