Using your hands or a knife, crumble the tempeh into small chunks.
In a medium bowl, stir together the soy sauce (or tamari), maple syrup, apple cider vinegar and vegetable broth. Marinate the tempeh in the mixture for at least 15 minutes, making sure all the tempeh gets covered.
To prepare the leek: Cut off the roots and the dark green tops- you won't be using these parts. Cut the remaining stalk lengthwise, then rinse in water to remove any dirt. Slice into ½ inch half moons.
In a large bowl, toss the vegetables in olive oil, salt, and pepper.
Combine the vegetables and marinated tempeh and spread into a thin layer on a large sheet pan. Roast for 30 minutes, stirring halfway through. Remove from the oven and enjoy!