This is a Moroccan recipe, which I first learnt while working as an intern at Alice Waters’ restaurant, Chez Panisse, in California.  ‘Herb jam’ is Paula Wolfert’s name for this delicious, savoury salad-cum-relish.  The recipe here is based on one of hers.
 
The key to success is patience.  You must wash vast quantities of greens and herbs, steam the greens, pound together the herbs and garlic, fry the olives and spices and then cook everything down together slowly in a wide pan until it resembles jam.  It’s a bit of a hassle, so I advise making a double batch (buy way more greens than you think it’s possible to cook) and freezing some.

But when you taste it, perhaps on crostini or with warm Moroccan bread, you’ll realise why this is such a special recipe.  If you love greens, olives and lemony flavours, you’ll adore this. Everyone I have cooked it for has found it a revelation.

For the greens, use a mix of whatever you can find - spinach, chard, rocket, kale, sorrel, watercress, mustard greens, celery leaves, purslane…