Rinse the white rice under cold water until clear and place it in a small pot with the beef stock and one minced garlic clove.
Bring the rice to a boil, then reduce heat to low, cover, and simmer for 15 minutes or until the liquid is fully absorbed.
Preheat your oven to 400°F and line a large baking sheet with parchment paper for easy cleanup.
Slice the carrot, capsicum, onion, and tomato into uniform bite-sized pieces and spread them across the prepared baking sheet.
Drizzle the vegetables with 0.5 tbsp of olive oil and season with a pinch of the sea salt and black pepper.
Roast the vegetables for 20 minutes, tossing halfway through, until they are tender and show golden caramelized edges.
Pat the barramundi fillets completely dry with paper towels and season both sides with the remaining salt, pepper, and dried oregano.
Heat the remaining 1 tbsp of olive oil in a large non-stick skillet over medium-high heat until shimmering.
Place the fish skin-side down in the pan and sear for 4-5 minutes without moving them to ensure the skin becomes perfectly crispy.
Carefully flip the fillets and cook for an additional 2-3 minutes until the flesh is opaque and flakes easily with a fork.
Fluff the savory beef-stock rice with a fork and serve the barramundi on top with the roasted vegetables arranged on the side.