Edgar Sia II engaged in business at twenty years of age. He opened the first branch in December 2003 at the Robinson's Mall Carpark-Iloilo.

Mang Inasal at Nepo Mall in Angeles City.

In 2003, he opened Mang Inasal. The restaurant was instantly successful that it spread throughout most of the Visayas, to Mindanao and then Metro Manila. It applied for franchise a couple of years later.^[1]

By 2009, Mang Inasal opened one hundred stores.