See Bolte u. Polívka 2:1-18. The story is composed of three episodes. (1) A nephew sells to his miserly uncle a means for making pots self-cooking. (2) In revenge, he is put into a bag to be thrown into the sea; exchanges places with a shepherd and gets his sheep, (3) then pretends to his uncle to have got them under-seas and persuades him to try the same means of enriching himself. The first is a modification of the self-cooking vessel, which is episode C in Bolte u. Polívka's analysis.
Compare Clouston, Popular Tales 2:243, 263, for Norse (Dasent) and Italian (Crane) parallels; Espinosa, Pedro de Ordimales cycle, JAFL 27:169, and discussion, 220-221.
The second and third are episodes H and J in Bolte u. Polívka. See numbers 23 and 108 in this collection.