Preheat the oven to 400°F.
While oven is heating, wash and dry potatoes, then chop into 1/4" cubes. Spread in a single layer on a nonstick or prepared baking sheet. Season with salt and pepper to taste.
Roast 10-12 minutes, then flip. Allow to roast another 10-12 minutes until the potatoes are browned and crispy. If desired, switch oven settings to broil for the last 3-4 minutes of roasting.
Meanwhile, gently whisk together the eggs and scramble in a non-stick or cast iron skillet until cooked to your preference. If desired, heat tortillas in the warm skillet before building the tacos.
To build the tacos: add the fresh spinach, then layer the scrambled eggs and roasted potatoes on top. Drizzle 1/2 tablespoon of chimichurri sauce over the top of each taco, then sprinkle with cheese. One serving equals two tacos and one tablespoon of chimichurri sauce.
Serve immediately.