A potherb, or pot herb, was a term widely used in the 16th to 19th centuries to refer to any plant with stalks and leaves that could be boiled as greens or used in soups. It also refers to cooking herbs, as opposed to medicinal herbs. That doesn’t really narrow your choices down much; we’d suggest using whatever fresh herbs you particularly like in your grandmother’s recipes.
How do I determine how much orange oil to use in place of grated orange peel? What would the ratio be?