Preheat the broiler. Place the peppers on a baking sheet covered with foil and broil until the skin is blistered and just charred, turning to cook on all sides as needed and removing them as they are finished. Place the charred peppers in a bowl and cover to steam for 10 minutes.
Open peppers, removing stems, seeds, and ribs. Turn the peppers over and flatten them out, peel the blistered skin off the peppers. Slice into 1/4 inch strips, lengthwise.
In the meantime, place the sweet potatoes in a microwave-safe bowl. Add about 1/4 cup water, cover with plastic wrap, and cook for about 5 minutes on high until potatoes are soft but still slightly firm.
Heat oil in a large skillet, add onion and saute until over medium-high heat until softened. Add potatoes and continue to cook until the onions are slightly browned and the potatoes pick up a bit of color. Optional, but add a little smoked paprika or chipotle powder to the potatoes if you wish. Add peppers, oregano, and cream and cook for a moment or two longer until the cream has thickened and coats the rest of the ingredients. Salt and pepper to taste.
Garnish as desired. A little cilantro, some sour cream or crema, and lime are fabulous.
Note: To prepare tortillas, if using flour they can be heated in a towel, a small stack at a time in the microwave for about 1 minute. If using corn, heat over a burner or in a dry skillet until slightly toasted but still soft and wrap in a towel to keep warm. A great time to do that is while the onions and sweet potato are being sauteed..
Keywords: Bell Peppers, Cheese, Cream, Heritage Recipe, Hot Peppers, Jalapeno, Meatless Meal, Mexican or Southwestern, Peppers, Poblano Peppers, Rajas, Red onion, Tacos, tortillas