Set oven rack about 6 inches from the heat source and preheat the oven's broiler. Line a baking sheet with aluminum foil; place chile pepper on top, cut sides down.
Cook under the preheated broiler until the skin of the pepper has blackened and blistered, 5 to 8 minutes. Place blackened pepper into a bowl and tightly seal with plastic wrap. Allow pepper to steam as it cool, about 10 minutes. Remove skin and chop flesh.
Heat oil in a cast iron skillet over medium-high heat; saute onion in the hot oil until golden, about 3 minutes. Stir in chile pepper and tomatoes. Bring to a boil; cook and stir until tomatoes soften and liquid is reduced by half, about 5 minutes.
Stir okra, salt, cumin, black pepper, and white pepper into the skillet. Cook, stirring gently, until okra is tender, about 5 minutes.