Celery leaves are the big, flat, blousy leaves that adorn the sides of fresh celery crowns. Some supermarkets cut them off, which makes me wonder where on earth they end up, but most of the cheaper packages leave them intact. I use them as a salad leaf in their own right, to flavour cold jugs of water in summer, whizzed up with oil and salt and vinegar to make an all-purpose dressing, and sometimes in this rather lah-di-dah pesto. You can make it more of a dip by thinning it with natural yoghurt, or use it as it is as a spread for crackers or hot bagels, in a toasted sandwich, or tossed through hot or cold pasta with a bit of black pepper. It makes a fab dressing for a potato salad, tossed through warm cooked potatoes – tinned ones are absolutely fine in this instance.
Place the peanut butter into a small blender, along with the celery leaves, blue cheese and parsley, including any stalks. Pulse briefly for a few seconds at a time to blitz it all together. Add a dash of the oil if needed to loosen it – not all peanut butters, nor cheeses, are created equal.
Shake the blitzed leaves and nuts into a clean jar. Pour almost all the remaining oil into the cup of the blender and measure in the vinegar. Briefly blend to a smooth, creamy liquid, and pour it into the jar. Stir everything to coat, then top up with the last bit of oil to form a seal between the pesto and the top of the jar, which will help keep it fresher for longer.
Seal tightly and store in the fridge for up to 5 days, or the freezer for 3 months. Defrost thoroughly before using.
© Jack Monroe, 2020