Add olive oil to a preheated, large, nonstick skillet or well-seasoned, cast iron skillet over medium-high heat.
Add sausage and cook 3-4 min per side. Transfer cooked sausage to a tray and set aside.
Add onions, peppers and garlic to the pan and season with a pinch of salt. Sauté for 6-8 minutes or until onions are soft. Stir regularly so as not to burn.
Season onion mixture with smoked paprika and cook additional 60 seconds. Add passata and cook 6-8 minutes or until slightly reduced. Add harissa and stir through to incorporate. Taste for seasoning and adjust as required. TIP: if tomato sauce becomes too thick, simply dilute with 1/2 cup or more of water.
Using a wooden spoon or spatula, create a small hole in the sauce and crack the egg into the hole you’ve created. This will help the egg to cook into the sauce, rather than over top of it.
Lower heat to med-low, cover pan with a lid and cook until the egg whites have firmed-up but the yolks are still runny – approximately 6-8 minutes.
Remove shakshuka from heat. Garnish with pitted olives and fresh parsley. Serve immediately.