Some original dishes from the Alentejo region can use cilantro quite heavily.
Portuguese word for cilantro is Coentros.
You can pre- write a piece of paper to show the waiter that you have an allergy to cilantro.
" Eu tenho alergia a coentros, por favor recomende comida sem coentros. Obrigada"
That translates to : I have an allergy to cilantro, please recomend food without cilantro. Thanks.
Some popular dishes that originally have cilantro:
Carne de porco á Alentejana - Pork meat with clams from Alentejo.
Carne de porco á portuguesa - pork meat without the clams.
Açorda - it's generally a bread based dish with other ingredients, many variations ( the original recipe is very heavy on cilantro)
Febras á Alentejana - porks steaks Alentejo style
Amêijoas á Bulhão Pato - clams Bulhão Pato style, anything Bulhão Pato has cilantro