Add the rice, water, cumin, chili powder, 1/2 tsp salt, and 1/8 tsp pepper to a small saucepan. Stir to combine and bring to a boil over medium-high heat. When water begins to boil reduce the heat to low and cover the pan tightly. Allow to simmer, covered (Do not remove the lid at anytime), over low heat for 10 minutes. Turn off the heat and allow the rice to sit, covered (Keep the lid on), for 15 more minutes.
Cut a slit lengthwise on one side of each of the poblano peppers. Lay the poblano peppers slit-side up onto a baking sheet. Roast the poblanos in the preheated oven for 10 minutes or until softened a bit. Take out of the oven and set aside to cool.
Heat the oil in a skillet over medium-high heat. Add the onion and cook, stirring occasionally, until softened, about 5 minutes.
Add the jalapeno, garlic, corn, and tomato to the pan and stir to combine. Cook while stirring until heated through, about 2 minutes. Take the pan off the heat and stir in the cooked rice, cilantro, and cheese until thoroughly combined.
When the poblanos are cool pry them open, rinse the inside of the poblanos out under cold water and scoop out any ribs and seeds. Spoon the rice mixture evenly into the poblano peppers. Bake in the oven for 15 minutes.