Heat 2 teaspoons of oil in a large saucepan on a medium-high heat. Cook chicken, stirring, for 2 to 3 minutes or until browned. Transfer to a bowl.
Reduce heat to medium to heat remaining oil in the pan. Add onion, mushroom, red pepper, garlic and paprika. Cook for 5 minutes or until the mushrooms are tender. Add tomato puree, a tin of tomatoes and 250ml cold water. Increase heat to high. Bring to the boil. Return chicken to pan. Reduce heat to medium-low. Cook, covered, for 20 minutes or until chicken is cooked through and the sauce has slightly thickened. Season with pepper.
Meanwhile, cook the pasta in a large saucepan of boiling water following packet directions, until tender. Drain.
Divide pasta and goulash between serving bowls. Top with sour cream. Serve sprinkled with chives.