Step 1

To a large pot (or pressure cooker; see footnote) set over medium heat, add the oil and garlic and cook until fragrant, about 2 minutes. Stir in the cumin, white pepper, turmeric, and saffron and cook for 1 minute more. Add the lamb and salt and stir to coat with the spices. Add the preserved lemon and enough water to just cover the meat, then bring to a boil. Cover, turn the heat down to maintain a strong simmer, and cook until the meat is soft and flakes apart easily, about 2 hours.

Step 2

Using a slotted spoon, transfer the lamb to a bowl. Turn the heat to medium-high and cook the broth, stirring occasionally, until thickened slightly and reduced by one third, about 10 minutes. Return the lamb to the pot and bring to a simmer, then remove from the heat.

Step 3

Transfer the tangia to a serving bowl (alternatively, serve straight from the pot) and garnish with parsley sprigs.