Rub the tilapia fillets with the soy sauce, salt, and pepper. Let sit at room temperature for 10 minutes.
Line a heavy pot or wok with foil, add the wood chips, and set a rack above them. Place the tilapia on the rack, cover tightly, and heat over medium heat until the chips begin to smolder, about 5 minutes.
Reduce the heat to low and smoke for 20 to 25 minutes, until the fish flakes easily and looks opaque throughout.
While the fish smokes, combine the stock, kombu if using, garlic, and ginger in a separate pot. Simmer gently for 15 to 20 minutes.
Remove the kombu. Take the pot off the heat, then whisk in the miso paste until dissolved. Stir in the soy sauce, rice vinegar, and sesame oil.
Return the broth to low heat to stay warm. Add the kale and let it wilt for 1 to 2 minutes.
Cook the noodles and divide among four bowls. Ladle the broth and kale over the noodles.
Flake the smoked tilapia on top, then add a soft-boiled egg half, scallions, sesame seeds, and chili oil if using.