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1
Stir butter, tarragon, mint, tarragon vinegar, and 2 teaspoons coarse salt in medium bowl until well blended. Transfer 1/4 cup herb butter to small bowl and reserve for vegetables. DO AHEAD:
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2
Cover both bowls and chill. Bring medium bowl of herb butter to room temperature before using.
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3
Using small sharp knife, make 1-inch-deep slits all over lamb. Insert 3 or 4 orange peel strips into each slit. DO AHEAD:
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4
Enclose lamb in plastic wrap and chill.
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5
Position rack in bottom third of oven and preheat to 450u00b0F. Heat oil in very large skillet over medium-high heat. Sprinkle lamb with coarse salt and pepper. Add lamb to skillet; cook until brown on all sides, about 8 minutes. Transfer to roasting pan. Brush with 2 tablespoons herb butter. Roast lamb 15 minutes. Brush again with 2 tablespoons herb butter.
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6
Reduce temperature to 350u00b0F. Continue to roast lamb until thermometer inserted into thickest part registers 135u00b0F to 140u00b0F for medium-rare, about 55 minutes. Transfer lamb to platter; reserve pan. Tent lamb loosely with foil; let rest 30 minutes.
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7
Spoon fat off any juices in roasting pan. Place pan over 2 burners on high heat. Add wine and broth and bring to boil, whisking to scrape up browned bits. Boil until sauce is reduced to 2 cups, about 5 minutes. Whisk in remaining herb butter and grated orange peel. Season sauce to taste with coarse salt and pepper.
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8
Spoon vegetables around lamb on platter; garnish with fresh herb sprigs. Serve with sauce.
