Brush a medium nonstick stick skillet lightly with olive oil and bring to medium heat. Add the spinach and pinches of salt and pepper and sauté until the spinach is wilted. Work in batches, if necessary.

Wipe out the skillet and scramble the eggs. Brush the skillet lightly with olive oil and bring to medium heat. Add the eggs, let them cook for a few seconds, and then stir and scramble the eggs until just set.

Assemble the tacos with the eggs, spinach, avocado slices, and scoops of tomatillo salsa. Top with the microgreens and sliced serranos and serve with lime wedges, if desired.