Pre-heat pan and cook the finely chopped onion and garlic until golden brown . Add the white wine and reduce by half add fish stock and again reduce by half than add the seafood butter and the cream and let simmer on low heat until thickened. In a separate dish brush the bell peppers with oil and roast for 15 minutes in oven 180`c. In a separate pan, boil the tagliatelle for 7 minutes,drain and add to the sauce garnish with the roasted bell peppers.