Preheat the grill to 325F.

To prep the leeks, trim the tops and bottoms almost to the roots. Split in half lengthwise and thoroughly clean in cool running water. Leeks can be very muddy, so separate the layers a bit to rinse them completely.

Arrange the leeks in a baking dish, cut side up.

Sprinkle the leeks with lemon zest, and squeeze the juice over all of the leeks.

Top with the thyme sprigs.

In a small sauce pot, warm the vegetable broth with the miso paste and olive oil. Whisk to combine until the miso paste has dissolved and the broth has come to a simmer.

Carefully pour the broth over the leeks.

Cover the dish with a piece of parchment paper and a layer of foil.

Place on the grill and braise at 325F for 45 minutes.

Uncover the leeks and raise the heat to 375F.

Continue to cook at 375F for 30-45 minutes until the broth has reduced quite a bit and the leeks have slightly caramelized.

Serve warm, room temperature.

Allow to cool completely before placing in the fridge if making in advance.