Cook the fettuccine in boiling, well-salted water according to the package instructions.
Meanwhile, heat the olive oil in a large frying pan over medium heat. Add the garlic and cook, stirring, for 30 seconds.
Add the Swiss chard and sea salt, and cook, stirring once or twice or until tender. Remove from the heat and cover to keep warm while the pasta finishes cooking.
When the pasta is ready, reserve ½ cup cooking water and drain the pasta. Add the pasta to the Swiss chard, along with the tomatoes, plant-based sour cream and crushed red-pepper flakes. Toss well, adding a little reserved pasta water if needed, and serve immediately.
