Ponzu Sauce

Hi Maki, Good day! I was wondering if you could share how you make ponzu sauce. I really enjoy tasting the ponzu from the Japanese restaurants. Tried making my own from a recipe I was given and did not care for the taste too much. It tasted quite different from the ones I have had at the restaurants. Do you actually make your own or do you buy the pre made bottles from the grocery store. If so, could you share which brand you actually buy? Thanks!