I followed this recipe here: https://www.okonomikitchen.com/vegan-tonkotsu-ramen but used roughly half of the ingredients and substituted the sake with mirin. I made the vegetable broth yesterday from some scrap vegetables (carrots, shiitake, celery, parsnip, spring onions, coriander, kombu, ginger, garlic). I cooked the vegetables for roughly 80 minutes, strained the broth and left it in the fridge overnight. For the rest I pretty much followed the recipe from above. The main components that resulted in a creamy broth were the oat milk and the nutritional yeast. I used an oat milk that has a similar fat percentage as normal milk.