1.Heat half the oil in 6-litre (24-cup) pressure cooker; cook beef, in batches, until browned. Remove from cooker.
2.Heat remaining oil in cooker; cook onion, garlic and spices, stirring, until onion softens. Return beef to cooker with undrained tomatoes and stock; secure lid. Bring cooker to high pressure. Reduce heat to stabilise pressure; cook 15 minutes.
3.Release pressure using the quick release method; remove lid. Stir in spinach, olives and preserved lemon; simmer, uncovered, until hot. Season to taste. Serve tagine sprinkled with nuts.
If you have an electric pressure cooker you won’t need to reduce the heat to stabilise pressure, your cooker will automatically stabilise itself. Always check with the manufacturer’s instructions before using. Preserved lemons, a prominent ingredient in North African cooking, are salted lemons bottled for several months; the flavour is salty, unique and perfumed.