Put the spinach in a large bowl and add enough water to cover. Swish to release the dirt and grit. Lift out and transfer to a colander. Repeat if the water is very dirty.
Heat the oil in a large skillet over medium heat. Add the peppers, onions, garlic, and a large pinch of salt. Cook, stirring occasionally, until the onion is translucent, about 5 minutes.
Add the tomato paste and cook, stirring, for 1 minute. Add the spinach by the handful, stirring to wilt after each addition. Sprinkle with salt and stir well, then spread in an even layer.
Crack an egg into a dish, then slide onto the spinach. Repeat with the remaining eggs, spacing them apart. Reduce the heat to medium-low. Cover and cook until the whites are set and the yolks are runny, 3 to 5 minutes.
Meanwhile, toast the tortillas in a hot skillet or griddle until blackened around the edges and in spots. Immediately spread 1 teaspoon za'atar on each tortilla.
Uncover the eggs and drizzle the remaining 4 teaspoons za'atar spread all over the eggs and greens. Serve the shakshuka with the tortillas.
In this fresh twist on shakshuka, the eggs are cooked in a bed of spiced spinach instead of tomato sauce.
Recipe by Genevieve Ko.