With 'difficult' meat sauces - the taste stays 'flat' - reduce 100ml of good quality wine vinegar (spirit vinegar will only go bitter!), to about 50ml in a fast boiling pan. Add a squeeze of lemon juice and a pinch of salt; add this mixture into the sauce, teaspoon by teaspoon until the flavour pops!
Note: if the sauce is slightly 'bitter' (burnt pan bitter) - add a pinch of salt - it will help!