Heat a large skillet with olive oil and 1 tablespoon butter. Season the fillets with some salt and pepper. Place fillets in skillet and cook about 5 minutes on each side. When the fish is cooked, set aside on a plate and deglaze the pan with the vermouth, add the thyme and saffron leaving to bubble until it's reduced by two thirds. Add remaining butter and whisk followed by the heavy cream and heat through. Serve fillets with light saffron cream sauce and blanched asparagus.