Start by washing and chopping all the vegetables. I like having everything ready before turning on the heat because the cooking moves fast. Beat the eggs lightly in a bowl and set them aside.
Heat olive oil in a non-stick skillet over medium heat. Add the onion, bell pepper, and zucchini, and cook until they soften. Stir often so they cook evenly without browning too much.
Add the diced cooked potatoes to the skillet and let them warm through. Toss in the fresh spinach and cook just until it wilts, which only takes a minute.
Lower the heat slightly and pour the beaten eggs over the vegetables. Gently stir with a spatula, letting soft curds form. Season with salt and pepper as the eggs cook.
Once the eggs are just set, remove the skillet from heat. Spoon the scramble into bowls and top with sliced avocado and fresh herbs. Serve immediately while warm.