i am looking for a book
Thanks for asking! I played around with a few different searches, but the nature of Mills & Boon and Harlequin imprints makes traditional 'find this book' tools pretty weak, and I wasn't able to find a great fit for you. If you remember what Mills & Boon imprint/series the book was from (list from RomanceWiki) it may help you narrow your search. The 'Modern Romance' series Self-Made Millionaires might be a good place to start looking - seems like the male leads are self-made millionaires (natch) and mostly from Mediterranean backgrounds where strong, sweet tea is common.
Failing all else, you can brute force your way through this FictionDB index of Mills & Boon titles. It's mostly chronological, so if you remember more or less when you read the book or when it was published you can skip a few decades. Happy hunting!