Bring a large pot of salted water to a boil for the penne; bring a small pot of water to a boil for the eggs. While the water heats:

• Peel and chop the onion into ¼-inch pieces.
• Finely chop enough garlic to measure 1 teaspoon.
• Remove the stem, ribs, and seeds from the green bell pepper; cut the pepper into ¼-inch pieces.
• Cut the cherry tomatoes in half.
• Shuck the corn; lay the ear flat and cut the kernels from the cob.
• Trim the root ends from the scallions; thinly slice the scallions.
• Juice the lime.

Fill a bowl with ice water. Carefully lower the eggs into the small pot of boiling water; boil for 5 minutes for soft-boiled, 8 minutes for hard-boiled. Transfer the eggs to the ice water to cool. Peel carefully. While the eggs cook, start the penne.

Add the penne to the large pot; boil until just tender, 8 to 10 minutes. Drain, reserving ¼ cup cooking water. While the penne cooks, start cooking the vegetables.

In a pan over medium-high heat, warm 2 tablespoons oil until hot but not smoking. Add the onion and garlic and cook, stirring, until softened, 2 to 3 minutes. Add the bell peppers and tomatoes; cook until the tomatoes release some of their juices, 2 to 3 minutes. Stir in the corn, scallions, and as much Hot Cajun seasoning as you like. Cook until heated through, about 1 minute. Remove from the heat.

To the vegetable mixture, stir in the drained penne, 2 tablespoons pasta cooking water, and the lime juice; stir until well combined. Stir in the remaining pasta cooking water if dry. Season to taste with salt and pepper.
Cut the eggs in half lengthwise.

Transfer the penne and vegetables to individual plates. Top with the eggs and serve.

To get dinner on the table even more quickly, start cooking the onion and garlic while you prep the rest of the vegetables.