Heat a large pot over medium-high heat. Once hot, add oil, garlic, ginger, and onion. Sauté, stirring occasionally for 5-8 minutes or until the onion has developed a slight sear (browned edges).
Add curry paste and sauté for 1-2 minutes more, stirring frequently. Then add vegetable broth and coconut milk and stir to deglaze the bottom of the pan.
Bring to a simmer over medium heat, then reduce heat to low and cover. Simmer on low for at least 1 hour, up to 2-3, stirring occasionally. The longer it cooks, the more the flavor will deepen and develop.
Taste broth and adjust seasonings as needed, adding coconut sugar for a little sweetness, turmeric for more intense curry flavor, or more sesame oil for nuttiness.
About 10 minutes before serving, prepare any desired toppings/sides, such as noodles, sautéed portobello mushrooms, or green onion (optional).
Just before serving, scoop out 1/2 cup of the broth and whisk in the miso paste. Once fully dissolved, add back to the pot and turn off the heat. Stir to combine.
Either strain broth through a fine mesh strainer (discarding onions, garlic, and ginger or adding back to the soup) or ladle out the broth and leave the onions, garlic, and ginger behind.
To serve, divide noodles of choice between serving bowls. Top with broth and desired toppings. Serve with chili garlic sauce or sriracha for added heat.
Best when fresh, though the broth can be stored (separate from sides/toppings) in the refrigerator for up to 5 days or in the freezer for up to 1 month.
*You can sub sesame oil for coconut, but the sesame adds a nice rich nutty flavor to the ramen that I prefer. *Nutrition information is a rough estimate calculated using brown rice noodles and mushrooms with no additional toppings. *If using ramen noodles, this recipe would not be gluten free.