1. Heat 2 tablespoons oil in a Dutch oven over medium heat. Add pasta pieces and cook, stirring, until toasted and browned in spots, 2-3 minutes. Transfer to a bowl.
2. Add the remaining 1 tablespoon oil to the pan and heat over medium heat. Add green beans, onion and garlic and cook, stirring until the green beans are beginning to soften, 3-5 minutes. Add tomatoes, corn, oregano, and cook, stirring until the tomatoes are just beginning to break down, 1-2 minutes. Stir in broth, salt and the toasted pasta, bring to a boil over high heat.
3. Reduce heat to medium-low, cover and cook, stirring once or twice, until the pasta is tender and most of the broth is absorbed, about 10 minutes. Server topped with cheese and scallions, with lime wedges on the side.
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