Prepare peanut sauce by combining peanut butter, soy sauce, sesame oil, garlic, ginger, jalapeño, sriracha and 1/4 cup of water in a food processor, blender or mixing bowl (if using an immersion blender). Blend on high until smooth - adding additional water if needed.
Fill a pot with water and bring to a boil. Add soba noodles and cook according to package instructions. Soba noodles should only take 4-6 minutes to cook. Be sure not to overcook them. Drain and set aside.
Two minutes before noodles are finished cooking, heat remaining sesame oil in a pan over medium-high heat. Add bell pepper and cabbage and sauté for 2 minutes - making sure not to overcook (you want a little crunch).
Turn heat off and add cooked noodles & peanut sauce to the pan. Stir to combine. If the sauce is too thick you can add 1/4 cup of water to the pan to help thin out the sauce and coat everything better.
Serve noodles immediately and top with green onion, cilantro and peanuts.