The owner and CEO of the Burrito King restaurant franchise, Burrito Royale is self-described as simply a humble man who greatly enjoys burritos and the joy of providing good food to his customers, and happens to be named Burrito himself (since his parents loved burritos a lot as well). He owns and operates the restaurant himself, and is apparently very popular with his customers.
One day, Zim comes to the Burrito King, intent on conquering it as an easy victory, in order to one-up Invader Larb. After confirming that Burrito is in charge, Zim chases him off and takes control of the restaurant for himself. Burrito runs away, swearing to come back and avenge himself.
Later on in the comic, Burrito does so. He reveals that he went off on a long quest - despite the fact, as Dib (who's with him) points out, he only left that morning - gathering followers, and finally accepting his destiny, as the last person in the world to have the power to control beans (though he refuses the title of "beanbender"). He then set forth to take back his restaurant.
Zim's new followers quickly abandon him in the face of Burrito's own army and powers, but an undaunted Zim transforms his new throne into a battle suit called "Mecha-Rito" and prepares to fight. However, Burrito merely has his followers trigger a booby trap he had lying around for some reason, destroying the Mecha-Rito. Burrito then uses his powers to banish Zim and GIR from the Burrito King, regaining control of it.
Dib states that Burrito truly is a beanbender, and while he denies the title, the final panel shows a movie is made about him using it.