How to use annatto paste?

Sorry if this isn’t the right sub for this, I couldn’t find annatto seeds anywhere near me just the paste that’s like a brick of red powder, the instructions say to just whisk it into hot oil or vinegar but the powder always separates out into hard chunks leaving very little color in the liquid once it’s heated. I’ve tried whisking it longer adding when it’s cold adding it when it’s hot but it always separates am I doing it wrong?