Preheat the oven to 200 degrees Celsius. Clean the carrots and zucchini. Cut the 100 grams of carrots and 100 grams of zucchini into thin, uniform strips so that the vegetables cook at the same time as the fish. Lay out a large piece of parchment paper on the counter or on a baking sheet.
Distribute the sliced carrots and zucchini over the center of the parchment paper. Place the 150 grams of cod on top of the vegetables. Cut the lemon in half, squeeze one half over the fish, and slice the other half into slices to place on the cod. Fold the edges of the parchment paper carefully and tightly closed, creating a sealed packet from which no steam can escape. Slide the parchment packet into the oven and bake until cooked through, about 20 minutes.
Remove the fish packet from the oven after cooking and let it rest closed for one minute. Carefully open the parchment paper and be careful of the hot steam that will be released. Slide the cod, vegetables, and cooking liquid directly from the paper onto a plate and serve immediately.