。
She recommended the blue tie to the customer.
Literal
She [topic-は] that customer [to-に] blue [genitive-の] necktie [object-を] recommended.
勧める ('to recommend, suggest, urge') is the verb of choice when offering advice or pushing a particular option toward someone — both a shop attendant suggesting a product and a friend recommending a movie use 勧める. Note the case marking: に for the recipient of the recommendation, を for the thing recommended. ブルー is the loanword equivalent of 青 ('blue'); in the world of fashion and product labels, the loanword often feels more sleek or upmarket than the native Japanese color word.