In casserole or tagine, fry the onions and garlic in 1 tablespoon olive oil on a low-medium heat until softened – this will take about 7 minutes. Stir in the turmeric and fry for another 2 minutes, then add the paprika, cumin, coriander and cardamom and continue frying over a low heat for a further 2 minutes. Transfer the mixture to a bowl and set aside.