Place freekeh in a small bowl and cover with cold water. Set aside.
Combine lamb, onion, pepper, paprika, cinnamon, and salt in a pot. Add 1/2 of the cilantro, 1/2 of the mint, celery stalk, and oil; mix well. Simmer over low heat for 15 minutes. Stir in chickpeas, pour in just enough water to cover, and return to a simmer. Stir in zucchini, carrot, and tomato paste.
Set a steamer over the pot and add tomatoes. Cover and steam tomatoes until soft, about 5 minutes. Crush tomatoes using a wooden spoon, so pulp drips into soup. Remove the steamer and discard leftover tomato peels.
Add potato to soup and just enough water to cover. Simmer until potato is soft, about 10 minutes.
Drain freekeh and add to soup. Simmer until soft, about 15 minutes. Remove celery stalk. Sprinkle soup with remaining cilantro and mint before serving.