1cupfennel(finely cut, plus 2-3 fronds per fillet)
each, salt & pepper(to taste)
1largelemon(thinly sliced for 6 slices)
Preheat your oven to 375 degrees F (190 degrees C). Place a sheet of parchment paper (rectangle, about the size of the baking sheet) with the curled sides down on the baking sheet.
Place the first half of the sliced leek, carrots, fennel, thyme and fennel fronds in the center of the parchment paper sheet, then place a cod fillet on top of the vegetables. Season with salt and pepper and top with 3 thin slices of lemon.
Drizzle 1 teaspoon of olive oil around the cod and vegetables, then place a second sheet of parchment paper over the top of everything (cod and vegetables) roughly matching the size of the base sheet of parchment paper.
Fold the first corner in a triangular shape toward the center, then make progressive smaller triangular folds working one direction (either clockwise or counter-clockwise) until you reach the beginning point of your folds. (see video)
Press down on the folds with something heavy (I grabbed my bottle of olive oil as it was nearby) all the way around the envelope. Repeat with your second half of the vegetables and the second cod fillet (or however many fillets you are preparing).
Place in the preheated oven and bake for 12 minutes. Remove from the oven and either open and carefully remove the entire stack of vegetables and cod, or serve in the envelope. *There will be a large amount of steam released when opened, slit the top open first to release the steam or open a side first.