Tashi Delek implies not just a kind of blessing of goodwill, but also a deeper meaning. That is, "there is a cause, there must be a result". But in any case, the answer is to say "Tashi Delek" (good luck and happiness), which is the best kindness and blessings to the other side.
Tashi Delek is a Tibetan saying of welcome and blessings. In Tibetan, if someone says "Tashi Delek", it can be translated as "welcome" or "good luck", and the answer should be "Tashi Delek, shu (fourth sound) "instead of" Tashi Delek".
more about：Tashi Delek meaning