Leviticus 3:4
3 Then the one presenting the offering must present a gift to the Lord from the peace-offering sacrifice: He must remove the fat that covers the entrails and all the fat that surrounds the entrails, 4 the two kidneys with the fat on their sinews, and the protruding lobe on the liver (which he is to remove along with the kidneys). 5 Then the sons of Aaron must offer it up in smoke on the altar atop the burnt offering that is on the wood in the fire as a gift of a soothing aroma to the Lord.
Onkelos Leviticus 3:4
3 And of the oblation of the sacred victim the fat that covereth the inwards, even all the fat that is upon the inwards, 4 and the two kidneys and the fat which is upon them on the sides, and the caul that is upon the liver with the kidneys, he shall remove. 5 And the sons of Aharon shall burn it at the altar, with the burnt offering which is on the wood upon the fire, an oblation to be received with grace before the Lord.
Notes and References
"... Sifra and the Babylonian Talmud, Berachot 40a, admit that Scripture's hakesalim is obscure, and scholars differ as to which fat is meant. Saadiah opted for a general indefinite statement, 'inner organs.' Rashi translates it as 'flanks' and identifies it as the fat on the kidneys. Ibn Ezra derives the meaning from kesil, certain 'stars' in Isaiah 13:10 that flanked different sides of a constellation. Onkelos's gisesiya is the Aramaic term that replaces Scrip.ture's 'side,' in Targum Jonathan to Isaiah 60:4 and 66:12, and it is the frequent talmudic usage for 'side,' such as the phrase Ridakh gisa, 'to the other side' ..."
Drazin, Israel, and Stanley M. Wagner Onkelos on the Torah, Leviticus: Understanding the Bible Text (p. 14) Gefen, 2006