Heat a medium pan over medium heat. Add almonds and toast, stirring occasionally, for 2-4 minutes, until golden and toasted. Transfer to a small bowl and set aside.
In a small bowl, combine the smoked paprika, coriander, turmeric, and a generous amount of freshly ground black pepper.
Rub the fish all over with olive oil and sprinkle generously with Kosher salt. Rub a little less than half of the spice mixture on the fish, reserving the remining for the stew.
Heat the avocado oil in the same pan used to toast the almonds over medium heat. Add the onions, green peppers, a big pinch of Kosher salt, and cook, stirring occasionally, until slightly softened and just starting to brown, 4-6 minutes.
If pan is looking dry, add another drizzle of avocado oil. Then add the remaining spices and cook, stirring often, for 30 seconds. Add the diced tomato and garlic and cook, stirring often, until the tomato has softened, 1-2 minutes.
Add the harissa paste, vegetable stock, olives, chickpeas, and ½ teaspoon Kosher salt (double the amount of salt if doubling the recipe) and bring to a simmer. Cook for 2 minutes, then add the fish, nestling the pieces into the chickpeas. Top each piece of fish with 2 slices of lemon. Cover and cook for 6-7 minutes, until fish is cooked through.
Uncover and remove from heat. Swirl in butter, until melted. Taste and season with Kosher salt and freshly ground black pepper, if needed. Add a squeeze of lemon juice, if desired. Serve sprinkled with the toasted almonds and fresh cilantro leaves.