Heat oil in a large soup pot over medium heat. Add the garlic, ginger, and onion and cook for 5–8 minutes, stirring occasionally, until the vegetables soften and develop a slightly golden color.
Add 1 cup of vegetable broth and scrape the bottom of the pot with a wooden spoon to release any flavorful browned bits.
Pour in the remaining vegetable broth, dried shiitake mushrooms, and soy sauce. Bring the mixture to a gentle simmer.
Reduce the heat to low, cover partially, and allow the broth to simmer for 45–60 minutes. The longer it cooks, the deeper and richer the mushroom flavor becomes.
Strain the broth through a fine mesh strainer, removing the onion, ginger, garlic, and mushroom pieces. Return the broth to the pot.
Whisk the miso paste with a small amount of warm broth in a bowl until smooth. Stir the miso mixture, sesame oil, rice vinegar, and mirin into the broth. Avoid boiling after adding miso to preserve its flavor.
While the broth simmers, prepare the toppings. Heat oil in a skillet over medium heat and add the tofu cubes. Cook for 5–7 minutes, turning occasionally, until golden and lightly crispy.
Add the sliced mushrooms to the skillet and cook for 4–5 minutes until tender and browned.
Cook the ramen noodles according to the package instructions. Drain well and divide between serving bowls.
Pour the hot mushroom broth over the noodles. Add crispy tofu, sautéed mushrooms, bok choy, carrots, and green onions.
Finish each bowl with chili crisp, sesame seeds, nori strips, or extra soy sauce as desired.
Serve immediately while the broth is hot and the noodles are perfectly chewy.