In a medium bowl, combine the cabbage, carrot, and bell pepper. In a small bowl, mix the miso paste, olive oil, ginger, maple syrup, juice of 1 lemon, and a pinch of salt until smooth (miso paste can be a little hard to get smooth, so you can whiz it in the blender if needed). Pour the dressing over the cabbage mix, and use your hands to work it into the cabbage. Taste and add more lemon juice or salt if you like. Depending on how big your lemons are, you might need to use the juice of 2 lemons to balance out the miso.