1. Lay chiles on their sides on a metal rack set over grates of gas burners set on moderately high. (Or broil chiles on rack of a broiler pan about 2 inches from heat.) Roast chiles, turning them with tongs, until skins are blackened, 5 to 8 minutes. Transfer chiles to a bowl, then cover and let steam 10 minutes.
2. Peel poblanos and discard seeds and ribs, then coarsely chop. Peel jalapeno and chop with seeds (omit seeds if you want a less spicy salad). Transfer chiles to a large serving bowl and stir in tomatoes and herbs.
3. Toast pumpkin seeds in a dry well-seasoned 9- to 10-inch cast-iron skillet over moderate heat, stirring, until puffed and lightly browned, 2 to 3 minutes (seeds will pop as they puff). Transfer seeds to a small bowl.
4. Add half of corn to skillet and dry-roast over moderate heat, stirring frequently, until browned in spots, 4 to 5 minutes. Transfer to tomato mixture and cook remaining corn in same manner, adding it to tomato mixture.
5. Add onion to skillet and dry-roast, turning frequently, until browned but still slightly crisp. Transfer to a cutting board and coarsely chop. Stir into corn mixture.
6. Cook garlic and cumin in oil in skillet over moderate heat, stirring, until fragrant, about 30 seconds. Stir into corn mixture and season vegetables with salt and pepper.
7. Cook pasta in a large pot of boiling salted water until al dente, then drain. Add pasta to corn mixture and toss. Season with salt and sprinkle with pumpkin seeds and cheese. Serve warm or at room temperature.

Yield: 6 servings