If I am cutting onions/garlic and sauteing them to be eaten with fish, is it ok to use a fleishig knife and frying pan?
It is preferred not to cut them with a fleishig knife or to fry them in a fleishig pan if you are planning to eat them with fish. In retrospect though if it was alreadty done, then it may be eaten together.
Shevet Halevi 6-111(4), Arugas Habosem Y:D 95 ftnt. 3, Megilas Sefer 95-10.