Linguine with fennel orange and crab

Name: Linguine with fennel, orange, and crab
Ingredients: 2 tablespoons butter; 1 head of fennel, thinly sliced; 1/2 cup dry vermouth; 3/4 cup low sodium chicken stock; 1 pinch saffron threads; 1 bunch tarragon, leaves rinsed and removed; 2 cups golden tomatoes, roughly chopped; 3/4 cup creme fraiche; 1 orange; 1 pound fresh linguine; 1 pinch red pepper flakes