Heat the olive oil in a large skillet or cast-iron pan over medium heat. Add the diced onion and red bell pepper, sautéing for about 5-7 minutes until the vegetables are soft and the onion becomes translucent.

Stir in the minced garlic, harissa paste, cumin, and smoked paprika. Cook for another 1-2 minutes, stirring constantly until the spices are fragrant and coat the vegetables evenly.

Pour in the crushed tomatoes along with their juices, and season the mixture with salt and black pepper. Reduce the heat to medium-low and let the sauce simmer for 10-15 minutes until it thickens slightly and the flavors meld together.

Use a spoon to make small wells in the tomato sauce, then carefully crack an egg into each indentation. Cover the pan with a lid and cook for 5-8 minutes, or until the egg whites are set but the yolks remain runny to your liking.

Remove the pan from the heat and immediately garnish with chopped cilantro and crumbled feta cheese if using. Serve the Chakchouka straight from the skillet with slices of crusty bread for dipping.