Preheat oven to 400°F. Place potato rounds in one layer across a couple of non-stick cookie sheets. Drizzle with olive oil (or spray with cooking spray), salt, and pepper. Roast 20 minutes or until browned and crispy, flipping halfway through.

While the potatoes cook, heat 1 tsp olive oil on medium high until hot. Add the peppers and cook, stirring occasionally, 2 to 3 minutes, or until browned and softened; season with salt and pepper. Set aside.

Add 1 tsp olive oil, if needed. Add the garlic and shallot; season with salt and pepper. Cook, stirring frequently, 30 seconds to 1 minute, or until softened and fragrant. Add the corn; season with salt and pepper. Cook, stirring occasionally, 2 to 3 minutes, or until lightly browned and slightly softened. Add half the oregano and cook, stirring occasionally, 30 seconds to 1 minute, or until fragrant.

Combine potatoes, corn, and peppers, and set aside.

Pat the cod fillets dry with paper towels. Season with salt and pepper on both sides. In the same pan, heat butter and 1 tsp of olive oil on medium-high until melted and hot. Add the seasoned fillets and cook 2 to 3 minutes on the first side, or until browned. Flip and slowly add the vinegar. Cook, occasionally spooning the sauce over the fillets, 1 to 2 minutes, or until thoroughly coated and cooked through. Transfer to a plate, leaving the sauce in the pan.

Drizzle sauce over the cooked veggies. Serve cod over top and garnish with oregano.