Wash and dry the mustard greens. Then, cut off the stems.
Add the leaves to a food processor and chop until fine.
Once chopped, transfer them to a strainer and squeeze out the liquids.
Add them to a bowl, and add the finely chopped jalapeno, salt, and yogurt. Mix everything well.
Transfer the mixture to an airtight container and let it cure in the fridge for at least 7 days before eating.
Serve with a generous drizzle of extra virgin olive oil, and khobz kmaj, aka pita bread.
