Mustard greens had caught my eye, then this recipe was in the next issue, so decided to give it a go. Was pleasantly surprised! The bite of the mustard greens, the tang of the vinegar, the saltiness from the parmesan, the slight sweetness from the peas. I was without toasted walnut oil so used toasted walnuts and added enough olive oil to make it mix. This is a drier, coarser pesto. Just go with it.