In a large bowl, mix the ground beef, chopped herbs, celery, and onion until well combined. Stir in the breadcrumbs, olive oil, egg, Ras el Hanout, and salt, and mix until fully incorporated.
Trim the zucchinis and slice them in half lengthwise. Using a small spoon, carefully hollow out the center of each half to create space for the filling. Stuff each zucchini generously with the meat mixture, pressing gently to secure.
Prepare two shallow bowls: one with flour and another with beaten eggs. Lightly coat each stuffed zucchini in flour, then dip in the beaten egg. Heat the olive oil in a large skillet over medium heat and fry the zucchinis until golden brown on both sides, about 3 minutes per side. Transfer to a plate lined with paper towels.
In a wide, heavy-bottomed pot, heat the olive oil over low heat. Add the chopped spinach and cook slowly, stirring occasionally, until it wilts and darkens, about 20 minutes. Stir in the celery, green chili, leek, and garlic, and continue cooking for another 10 minutes over medium heat, allowing the vegetables to soften and develop flavor. Add the preserved lemon, cumin, salt, and black pepper, stirring to combine.
Pour in the water and bring the sauce to a gentle boil. Nestle the fried stuffed zucchinis into the pot, ensuring they are partially submerged. Reduce the heat to low, cover, and let them simmer for 1 hour, allowing the flavors to meld and the zucchini to soften. If the sauce is too thin at the end of cooking, uncover the pot and simmer for an additional 10 minutes to reduce the liquid.
Serve warm, spooning the rich sauce over the zucchinis.