Preheat your oven to 400 degrees F (200 degrees C). Line a large rimmed baking sheet with parchment paper.
In a large bowl, toss the halved baby potatoes with 2 tablespoons of olive oil, half of the dried herbs, salt, and black pepper. Spread them evenly on the prepared baking sheet and roast for 20 minutes.
Remove the baking sheet from the oven. Push the potatoes to the edges to make room for the fish in the center. Add the cherry tomatoes to the pan.
Place the cod fillets in the center of the baking sheet. Drizzle with the remaining 1 tablespoon of olive oil, and season with the rest of the herbs, salt, and pepper.
Return the baking sheet to the oven and bake for another 12-15 minutes, or until the cod is opaque and flakes easily with a fork, and the tomatoes have slightly burst.
Serve immediately, squeezing fresh lemon juice over the cod and roasted veggies.