Cook the noodles according to the package directions.
Meanwhile, in a large saucepan, over medium heat, combine the coconut milk, tomato paste, chili powder, salt, and chili paste or sauce (if using). Bring to a boil. Reduce heat and simmer for 2 to 3 minutes. Stir in the drained noodles and toss. Divide the noodles among individual bowls. Top with the scallions, sprouts, basil, and coconut (if using).
Tip: To toast shredded coconut, scatter it on a baking sheet and place in a 350° F oven until it's golden, 3 to 5 minutes. Watch carefully: It goes from toasted to scorched in seconds.