I am familiar with "Das schmeckt" to say you like the taste of something and I was working on a lesson in DuoLingo.com and used it in context a couple of times. I was looking up how to spell it, and found a few sites that mentioned "schmecken lassen" and gave "Tuck in" as the meaning. When I searched for "schmecken lassen", I mostly got more "taste" references, but a few more "tuck in" references.
How do "to taste" and "to tuck in" relate?
"Tuck in" is a British idiom that means the same thing as the American "dig in", i.e. go ahead and start eating (with relish).
"Lass es dir schmecken" is the colloquial/familiar variant of "Guten Appetit!" which then may be translated with "Enjoy your meal", or short "Enjoy".
The German equivalent of "tuck/dig in" would be the more casual:
Greif zu! - Hau rein!
The German "Lasst es Euch schmecken" or "Lassen Sie's sich schmecken" (familiar/polite) is used in a casual way instead of "Guten Appetit" or "Mahlzeit (casual, regional)" at the beginning of a meal.
To "tuck in", in American English, is commonly used to tuck somebody's sheets in at bed time. In British English, it is indeed also a colloquial expression to encourage somebody to start eating. A similar sounding equivalent to "Lasst es Euch schmecken" could be "dig in" instead:
[ in imperative ] (dig in) informal used to encourage someone to start eating with gusto and have as much as they want: put the sausage on top of the polenta; then dig in. (From the New Oxford American Dictionary)
On the other hand, the American English "dig in" is more similar to the German "greif zu" than to "Lasst es Euch schmecken".
