In a medium bowl, stir together the couscous, 1 tablespoon oil, the cumin, ¾ teaspoon salt and ½ teaspoon pepper. Stir in the boiling water; cover and let stand until the water is absorbed, 15 to 20 minutes.

Into the couscous, stir the olives, harissa, garlic and mozzarella. Add the eggs and flour, then stir until well combined; the mixture will be fairly wet. Refrigerate uncovered for at least 15 minutes or up to 1 hour.

In a 12-inch nonstick skillet over medium-high, heat the remaining 2 tablespoons oil until shimmering. Using your hands, form the couscous mixture into 4 balls; place them in the skillet as they are shaped. Using a spatula, press each into a patty about 4 inches wide. Cook until golden brown on the bottoms, 3 to 5 minutes. Using the spatula, flip the patties, then reduce to medium and cook until golden brown on the second sides, another 3 to 5 minutes. Transfer to a paper towel–lined plate. Sprinkle with salt and serve hot.

Optional garnish: Lemon (or lime or orange) wedges OR fresh flat-leaf parsley (or cilantro) leaves OR both