The expression mi mero mole literally means 'my very own mole'. It is used to mean that some activity is precisely what I like the most or what I excel at, my area of expertise. It can also be used in reference to other people's tastes or abilities: tu mero mole or su mero mole.
Secretario General del sindicato: Es probable que tengamos que usar los recursos del sindicato de este ejercicio fiscal para un evento social con los trabajadores.
Vocal del sindicato: Hazte. Ya sabemos que el reventón es tu mero mole.
Chairman of the workers' union: It's likely that we will have to use the union's funds from this fiscal year for a social event with all the members.
Union board member: Your so full of it. We know well that partying your ass off is what you like the most.
The image below shows a plate of mole poblano (Pueblan mole). Notice the sesame seeds on top of the sauce and the Mexican rice as a side.