Heat grill to high. Brush both sides of tofu and chicken with oil and season with salt and pepper. Grill the tofu on each side for 2 to 3 minutes or until slightly charred, remove, and cut into thin slices. Grill the chicken for 4 minutes per side or until slightly charred and just cooked through, remove, and cut into thin slices.
Meanwhile, heat 2 tablespoons of oil in a medium saucepan on the grates of the grill or side burner on the grill. Add the shallots and garlic and cook until soft. Add the ancho powder and cook for 10 seconds. Add the tamarind mixture, vinegar, fish sauce, brown sugar, and peanut butter and bring to a boil. Place the cooked noodles, tofu, and chicken in a large bowl. Pour the boiling sauce over the noodles and toss gently until until combined. Fold in the green onion, cilantro, and bean sprouts and top with the chopped nuts. Serve with grilled limes on the side.