When translating 'to lie in', as in 'to be located in' figuratively speaking, estar, radicar (hallarse o estar ubicado en), estribar (estar fundado/basarse en), or residir en are good options. In spoken Spanish, estar en, although less specific, is by far the most common option to convey this idea, while radicar, estribar, and residir tend to be more formal.
-El secreto está en la cocción — The secret lies in/is in the cooking
-El problema radica en su actitud — The problem lies in his attitude
-La dificultad estriba en la traducción — The difficulty lies in the translation
-La gracia reside en su tamaño — The charm lies in its size
