onion, finely chopped
carrots, finely chopped
mushrooms, coarsely chopped
tarragon, fresh minced
Combine onion, carrot, 1 garlic clove and 1 1/2 teaspoon olive oil in heavy medium saucepan; cook over low heat until veggies are tender, stirring frequently, about 8 minutes.
Add curry powder and saute 2 minutes.
Add stock and rosemary and bring to a boil.
Reduce heat to medium and cook until reduced to 2 1/2 cups, about 25 minutes.
Strain through sieve set over bowl, pressing on solids.
Heat remaining 1 1/2 teaspoon olive oil in heavy large nonstick skillet over medium-low heat; add mushrooms and cook until almost no liquid remains in skillet, stirring frequently, about 10 minutes.
Increase heat to medium-high; add shallot and remaining minced garlic and saute 5 minutes.
Add strained stock and boil until liquid is reduced to 2 cups, about 10 minutes.
Transfer to blender and blend until smooth, about 2 minutes.
Strain through a sieve, set over a saucepan.
Mix in lemon juice and season to taste with pepper.
(Can be prepared one day ahead. Cover and refrigerate.)
Bring sauce to a simmer, mix in tarragon and serve.
Serve over grilled pork, veal or chicken.