Make the Split Pea Broth: Heat oil in a large pot over medium heat. Sauté onion for 5–7 minutes until softened. Add garlic and ginger; cook 1 minute until fragrant. Stir in miso, soy sauce, split peas, broth, and water. Bring to a boil, then reduce to a simmer and cook 25–30 minutes, or until split peas are completely tender.
Blend the Broth: use an immersion blender to purée the soup until completely smooth and creamy. (Or transfer to a blender in batches.) Taste and adjust with salt, soy sauce, or a touch of chili crisp for depth and heat. If too thick, thin with a splash of broth or water.
Cook the ramen: Bring a separate pot of water to a boil. Cook noodles according to package directions. Drain and divide between bowls.
Assemble the Bowls: ladle hot split pea broth over the noodles. Top with jammy eggs, scallions, a drizzle of chili oil/chili crisp, and sesame seeds. Add nori if you like extra umami.