Best vegan ramen

Name: Best vegan ramen
Cuisine: Asian, Japanese
Ingredients: 2 Onions; 2 garlic bulbs; 2 large sweet potatoes diced; 2 tbsp vegetable oil; 1lb cremini mushroom; 8 ounces shiitake mushrooms; 2 celery stalks quartered; 2 green onions quartered; 2 thick slices of fresh ginger; Half head of Napa cabbage quartered; Tbsp sea salt; Tbsp ground pepper; 1 large piece kombu seaweed; 12 cups water; 1/3 cup low sodium tamari or soy sauce; 1/3 cup tahini; 2 tbsp red or white miso; 1 tbsp mirin; 400g ramen noodles; 1 carrot ribonned; 1 cup frozen corn thawed and drained; 4 green onions slices disgonally; 3 top sesame oil or chili oil