Step 1

Roast the poblanos and set them in a plastic bag to steam the skins off. Skin, then remove the tops and all the seeds. Slice them into strips crosswise. You can dice them if you prefer.

Step 2

Heat the butter in a large pan over medium-high heat. Add the onions and saute until wilted, about 3 to 5 minutes. Add the garlic, chiles if using, diced tomato, shrimp, oregano and salt and toss to combine. Saute until the shrimp turns pink, about 3 to 4 minutes. Mix in the cilantro and turn off the heat.

Step 3

Heat tortillas on a comal, griddle or large frying pan, or on a grill. Set the tortilla down, then add a generous portion of shredded cheese on it. As soon as the cheese starts to melt, spoon some filling into the center and fold the taco over. Press down with a spatula to set the taco, let it char just a bit on that first side, then flip to brown the other side. Serve at once.