Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
Peel and cube the sweet potato into 1/2-inch pieces and slice the carrots into rounds.
In a large bowl, toss the sweet potatoes and carrots with 0.5 tablespoons of avocado oil, half the sea salt, half the black pepper, and the dried thyme.
Spread the vegetables in a single layer on the baking sheet and roast for 20-25 minutes until tender and slightly caramelized.
While the vegetables roast, pat the cod fillet completely dry with paper towels and season both sides with the remaining salt and pepper.
Heat the remaining 0.5 tablespoons of avocado oil in a non-stick or cast-iron skillet over medium-high heat.
Place the cod in the hot pan and sear for 3-4 minutes per side until the fish is opaque and flakes easily with a fork.
Remove the pan from heat, drizzle the cod with lemon juice, and garnish with fresh chopped parsley.
Serve the pan-seared cod immediately alongside the roasted root vegetables.