Onions Boiled and then Broiled, circa 1684
At the end of an elaborate recipe, “To dress poached eggs,” Robert May, in his 1685 edition of The Accomplisht Cook says to “garnish it [the dish] with four or five whole onions boiled and broil’d.” (p. 441). In other words, after boiling the onions, they were to be grilled, presumably to give them color and augment their flavor.
Boiling vegetables first, and grilling them second, is sometimes suggested in modern cookbooks. For example, I have read a recipe that suggests boiling asparagus and then grilling it. While I have not found a recipe from the early modern or medieval period in which boiling and then grilling vegetables is mentioned — other than this Robert May reference to onions — I think it reasonable to assume that it was a method well within the cook’s repertoire.