1. Divide and shape sirloin into four 1-1/4-inch-thick oval patties. Brush both sides with oil and sprinkle evenly with pepper.
2. Heat oven to 350 degree F. Heat a 12-inch nonstick ovenproof skillet over medium-high heat, 2 minutes. Add patties and cook, 3 to 4 minutes. Turn and sprinkle with 1/4 teaspoon salt. Cook 3 to 4 minutes more, until both sides are well seared. Turn patties again and sprinkle tops with remaining 1/4 teaspoon salt. Place skillet in oven. Bake burgers 35 minutes, or until an instant-read thermometer registers 160 degrees F when inserted 1 inch from edge of each burger for medium.
3. Meanwhile, for the leek sauce melt butter in small saucepan over medium-low heat. Add leeks; cover and cook until leeks soften, 5 minutes. Increase heat to medium; stir in parsley, salt and cloves, if desired; cook uncovered 1 minute. Add wine and gently boil, until mixture is reduced to 1/2 cup. Gradually whisk in cream and boil, stirring, until sauce is reduced to 1 cup, about 10 minutes. Remove from heat. Set aside.
4. To prepare fried leeks, line a large plate with paper towels. Heat oil in medium saucepan over medium-high heat just until oil begins to smoke. Carefully add half of leeks and cook 3 minutes, until golden brown. Remove leeks with tongs or slotted spoon and drain on paper towels. Repeat with remaining leeks.
5. Reheat leek sauce over low heat. Divide sauce between 4 serving plates. Arrange burgers on top of each. Divide and mound fried leeks atop burgers. Makes 4 servings.