Alegar is the Middle English term for ale vinegar or malt vinegar.
Here’s a recipe for Sauge (whatever that is!) from a 15th century cookbook. Thanks to John Geck of Memorial University’s English department for sharing this with me. Now, who wants to translate?
Take Gyngere, Galyngale, Clowys, & grynde in a morter; þan take an handfulle of Sawge, & do þer-to, grynd wyl to-gederys; take Eyroun, & sethe hem harde, nym þe ȝolkys, grynde hem with þe Sawge & with þe spycis, & temper it vppe with Venegre or eysel, or with Alegere; take þe whyte of þe Eyroun, & sethe hem, & mynce hem smal, & caste þer-to; when it is y-temperyd, take Brawn of hennys or Fyssches, & ley on dysschys, & caste þin mete a-boue.