Source: The New York Times
Put a large pot of heavily salted water on to boil. Add the linguine, and cook until al dente.
While the pasta cooks, warm the crème fraîche over medium heat in a wide skillet. Stir in serrano or jalapeño pepper, mustard, and cayenne and season with salt and pepper. Add crab meat, stir to coat, and heat through, about 2 minutes.
Drain pasta and add to skillet with a few tablespoons (up to about 1/4 cup) of pasta water. Add the chives, scallions, tarragon, and basil. Toss gently to combine all the ingredients and coat pasta with the sauce. Squeeze fresh lemon juice over the pasta and toss once more. Transfer to a warm serving dish and garnish with additional herbs, if desired.