Bring a large pot of lightly-salted water to a rolling boil over high heat; add the fettuccine and return to a boil. Cook uncovered until the pasta has cooked through, but is still firm to the bite, about 8 minutes; drain.
Heat the olive oil in a large skillet or wok over medium-high heat. Fry the cumin seeds in the hot oil until they begin to pop, 2 to 3 minutes. Cook and stir the onion and garlic in the oil until lightly browned, about 5 minutes. Add the chicken and continue cooking until the chicken is cooked through, 4 to 5 minutes. Season with 1 tablespoon curry powder; cook and stir another 3 to 4 minutes. Pour the diced tomatoes over the mixture and reduce heat to low. Stir in the tomato paste and remaining 1 tablespoon curry powder. Simmer 15 minutes.
Stir the cooked pasta into the sauce to coat. Simmer 2 to 5 minutes, until pasta is reheated.