Sweet Pickled Baby Fennel and Plagiarism

This baby fennel gets used for the smoked salmon at the moment. I do like to use it for Asian dishes too.

The pickling liquid is made with rice vinegar, palm sugar, chilli and various spices. Once in the liquid I leave the fennel for at least 2 weeks before I use it so it requires some planning.

Today I saw the menu of the chef that just left me. Pretty much all his dishes on his new menu came from my personal recipe book. I am not happy to say the least. I expect that people who worked with me will use recipes they learnt, but to copy almost a whole menu (down to the exact same chutneys on the cheese board) is just out of order. Anyone else I told didn't react the same as I did but then they didn't put the time into researching all the recipes and testing the dishes etc. Am I wrong to think like this? What do I do about it?