Add the spinach, salsa, salt, and pepper and whisk to combine. Set aside.
Heat a small skillet over medium heat. Add the oil. Once hot, gently place the tortilla in the oil. I like to hold it with tongs and dip one side quickly before turning it over to cook. This allows both sides to fry more evenly.
Allow the tortilla to cook for 1-2 minutes until it begins to turn golden brown on the bottom with a few darker spots. Flip the tortilla and allow it to cook for about another minute on the other side until it is also golden.
Transfer the tortilla to a plate lined with a paper towel to absorb excess oil, then return the pan to the heat.
Add a little more oil if needed, then add the egg mixture to the pan. Cook, stirring frequently, until the egg is firm and cooked through.
To build the taco, layer cheese, then the egg mixture down the middle of the tortilla. Top with avocado slices, lime juice, hot sauce, and cilantro if desired.