Heat the oil in a heavy pot. Brown the beef in batches and set it aside.
Cook the onion for 8 minutes, add half the garlic and tomato paste, and cook for 1 minute. Return the beef, add stock, and simmer covered for 70 to 85 minutes until nearly tender.
Make the Seasoning:
Combine the ground walnuts, remaining garlic, coriander, paprika, fenugreek, cayenne, and salt.
Stir the walnut mixture, tkemali, and rice into the pot. Simmer uncovered for 18 to 22 minutes until the rice and beef are tender.
Finish:
Adjust the broth with more tkemali, salt, or a splash of water as needed. The soup should be lightly thickened but still brothy.
Rest for 10 minutes, stir in most of the fresh coriander, and garnish with the remainder.
Notes
Tkemali varies in tartness and salt, so adjust at the end.
Finely ground walnuts should enrich the broth rather than remain as coarse pieces.