1.Transfer the green buckwheat to a saucepan, cover with about 3 centimeters of water and bring to a boil.
2. Reduce to a simmer, cover, and simmer for 15 minutes or until the green buckwheat is tender but still has bite.
3. As the green buckwheat cooks, remove the outer husks and stems from the tomatillos, then rinse and quarter.
4. Transfer the quartered tomatillos to a blender or food processor with spinach and coriander. Blend/process until smooth.
5. Heat oil in a medium-sized skillet over medium heat. Add the onion and sauté for 3-4 minutes or until softened and fragrant.
6. Add the garlic, continue to sauté for another 30 seconds, then add the red pepper flakes and cumin. Stir for a few seconds to wake up those flavors.
7. Pour in the tomatillo puree – season with salt and black pepper. Cook for 15 minutes or until reduced and thickened, then fold in the cooked green buckwheat.
8. Use a large spoon to create four nests in the sauce for the eggs. Crack an egg into each nest.
9. Reduce heat to medium-low, cover the skillet and cook for 2-5 minutes or until the eggs are done to your liking.