In response to an old thread… To keep the fresh, light, flavor of the sauce try using mint as a substitute for the cucumber. Hot, spicy, cheesy, or oily substitutes didn’t work for my needs. Like the OP, my boyfriend doesn’t like cucumber. I cook his organically raised and self-processed staffordahire mutton/lamb frequently: lamb burgers, lamb meatballs, etc. and they need a light and fresh cucumber sauce or a reasonable substitute, in my humble opinion.