Heat 1 tablespoon olive oil in a cast-iron skillet over medium heat until shimmering, about 1 minute.

Slice cooked sausage into 1/2-inch coins and add to skillet. Cook undisturbed for 5 minutes until golden brown on one side.

Flip sausage coins and cook for 3 more minutes on the other side. Remove to a plate, leaving some oil in the skillet and reserving any extra.

Add diced red bell pepper to the skillet and cook for about 4 minutes over medium heat until softened with slightly charred edges. Add reserved oil if needed to prevent sticking. Remove to plate with sausage.

Add sliced zucchini to the skillet and cook for about 3 minutes over medium heat until tender-crisp. Add reserved oil if needed.

If using fresh corn, stand each cob upright in a large bowl and slice downward with a sharp knife to remove the kernels.

Combine cooked sausage, bell pepper, zucchini, and corn kernels back in the same skillet. Mix well.

Add reserved oil and chili powder to the skillet mixture. Reheat on low heat for 2-3 minutes to meld flavors.

Taste before adding salt, as sausage is usually quite salty. Season with salt only if needed.

Remove from heat and top with freshly chopped cilantro. Serve immediately.