Cook the noodles according to the package directions.
Meanwhile, brown the steak and sweet potato with the onion in the canola oil in a large pot over medium-high heat, 5 to 7 minutes.
Add the chicken broth, coconut milk, red curry paste, and Asian fish sauce; simmer until the potato is tender, 8 to 10 minutes.
Stir in the noodles and lime juice. Top with the basil and chili.