Mitochondrial triacylglycerol (TAG) lipase with activity toward long-chain diacylglycerols (DAGs) and triacylglycerols (TAGs) (PubMed:9544243, PubMed:19959834). Involved in mitochondrial lipid metabolism (PubMed:31483742). a triacylglycerol + H2O = a diacylglycerol + a fatty acid + H(+) 1,2,3-tri-(9Z-octadecenoyl)-glycerol + H2O = (9Z)-octadecenoate + di-(9Z)-octadecenoylglycerol + H(+) 1,2,3-tributanoylglycerol + H2O = butanoate + dibutanoylglycerol + H(+) 1,2,3-trioctanoylglycerol + H2O = dioctanoylglycerol + H(+) + octanoate di-(9Z)-octadecenoylglycerol + H2O = (9Z)-octadecenoate + (9Z-octadecenoyl)-glycerol + H(+) dioctanoylglycerol + H2O = H(+) + octanoate + octanoylglycerol Optimum pH is 8.0. Interacts with MIA40; forms mixed disulfide intermediates with MIA40. Imported into the IMS via the MIA40 disulfide relay system.