Heat the oil in a wok or a nonstick pan. Add the garlic, then add the tuna and cook for 3 to 4 minutes, breaking the pieces as it cooks. Add the onions and poblano chile and continue cooking for 2 minutes. Add the tomatoes and oregano. Season with salt and pepper.
Serve warm with tortillas and a squeeze of lime.
Cook's Note: Chuck uses a disca on the show, but a wok will get the job done too!