Mint Sauce for Lamb

Older recipes for English green sauce vaguely recommend finely chopping or grinding together herbs, vinegar or verjuice, and usually a bit of sugar or sometimes orange juice. Sorrel was most frequently called for, but parsley, spinach, and sometimes mint were also used. Green sauces were usually served with veal or roast lamb. The mint in this green sauce can be replaced with dill, sorrel, parsley, or spinach.