Preheat your oven to 400°F (200°C).

Peel and slice the gold potatoes and zucchini squash into thin rounds.

Combine all the sliced vegetables in a large mixing bowl along with salt, pepper, dried oregano, dried rosemary, chopped fresh parsley, and minced garlic. Toss gently until everything is coated.

Add the canned diced tomatoes (juice included) to the vegetable mixture and mix well.

Transfer this mixture to a roasting pan and drizzle generously with olive oil.

Scatter the thinly sliced red onion over the top of the vegetable mixture.

Roast in your preheated oven for approximately 75 minutes, checking for tenderness and a golden-brown appearance.