Bring 3-4 l salted water (1 teaspoon salt per litre) to the boil. Wash sage, shake dry, pluck leaves, chop half. Wash and quarter the tomatoes. Cook pasta in boiling salted water according to package instructions.
Dab meat dry. Fry in a grill pan in hot oil for about 3 minutes on each side. Season with salt and pepper and remove. Sauté sage leaves and tomatoes. Season with salt and pepper.
Drain the pasta, mix with pesto. Arrange steaks with butter, rest sage, tomatoes and noodles.