Place all of the miso vinaigrette ingredients except the oil in a blender. Purée until smooth. With the motor running, drizzle in the oil until emulsified. Season with salt and pepper.
For the tuna, combine the cilantro, garlic, soy sauce, lemon juice, sesame oil, brown sugar, ginger and sambal in a blender. Purée until smooth, adding water if necessary. Drizzle in the oil with the motor running until emulsified. Season with salt and pepper. Coat the tuna with the tamari vinaigrette.
Heat a grill or large skillet to high heat and sear each side of the tuna for 1-2 minutes, until browned. Slice on the diagonal.
In a large bowl, toss together the cabbages, onion, carrots, cucumber, edamame, radishes, cilantro and miso vinaigrette. Top with fried shallots and peanuts.
Divide the salad between plates and top with seared tuna.