Large green chilies are roasted and stuffed with a cheese-and-tomato filling. The stuffed peppers are then batter coated and fried.
1. Roast the chilies by sliding them under the broiler and cooking them until the skin is blistered and charred on all sides. Transfer the chilies to a bowl and cover with a clean kitchen towel. When cool enough to handle, lift off the skin with a paring knife. Cut each pepper down one side, leaving the stem attached. Scoop out the seeds and membrane, then set the chilies aside on absorbent paper.
2. In a large mixing bowl, combine the cheese, onions, and tomatoes. Toss to combine and spoon into the chili pepper cavities. Press the cut edges in slightly. Transfer to a plate and cover with plastic wrap. Refrigerate for 1 hour.
3. In a small bowl, whisk the egg yolks until they are slightly thickened. Whisk in the salt and baking powder, then whisk in the flour. In a separate bowl, beat the egg whites, until soft peaks form. Fold them into the egg yolk mIxture.
4. Heat 1 inch of oil in a large skillet. Dip the chilies into the egg batter and fry in hot oil. Turn the chilies once, cooking them until lightly browned. Transfer to absorbent paper to drain. Serve immediately.