If one had fish, fruit, and vegetables for dinner and then 1.5-3 pieces of cake/babka (either immediately after or after 20-45 minutes), is washing required?
It is controversial, if we include all of what the person ate into the calculation for “a meal’s worth” in regard to washing when eating cake etc. The best thing is to eat the vegetables, etc. then make a borei nefashos, which will separate it from the mezonos. Then eat your cake and the fish will definitely not be included with the cake as one meal.
M:B 268-24, Igros Moshe O:CH 1-56, Aruch Hashulchan 268-17, Shulchan Aruch Horav 168-Kaf Hachaim 268-47, Chazon Ish O:CH 26-8, Vzos Habracha pg. 33.