You first need to collect four ingredients to make Lost Ark Gold Sparkling Elemental Food. You will hopefully only need one of each ingredient, but do keep hold of any extras if you find them:

Purified Lotus Flower Water: Examine lotus flowers in the southwest of Glass Lotus Lake. Head west from the Flowstream Village Triport and take the path that heads southwest. First Contaminated Elemental Food: Go to the Contaminated Village Triport in Xeneela ruins, walk a little way northeast, and look for spots where you can investigate. Second Contaminated Elemental Food: This is a random Rohendel creature drop. The best drop rates come from elite (glowing) monsters, but anything may drop one. Third Contaminated Elemental Food: This drops when you defeat world boss Magmadon in the south of Xeneela Ruins.

Take these four ingredients to Cook Ailara in Rothun, who can make you Sparkling Elemental Food from them for 2,500 silver coins. When you right-click this in your inventory, it has a ‘high chance’ of turning into cheap Lost Ark Gold the Zechbas you need for your tome. But if it doesn’t, I’m afraid you’ll need to get the ingredients again.