Oven Roasted Orange Beef Tri-Tip with Shanghainese Sauce

Combine soy sauce and garlic in resealable plastic bag. Add roast and massage with marinade. Seal bag and refrigerate for at least 2 hours or up to overnight.
Heat oil in skillet over medium high heat. Remove roast from bag, reserving marinade and sear roast well on both sides; set aside.
Heat remaining oil in large pot and sauté green onions, ginger, star anise and cinnamon for 5 minutes or until fragrant. Add vinegar to deglaze the pot. Add beef and any juices to pot. Pour in 1 cup of water, reserved marinade and add orange peel to pot. Bring to a simmer.
Place in a preheated 275°F (140°C) oven; cook uncovered until thermometer reads 140°F (60°C) for medium, about 25 to 30 minutes, depending on thickness of roast
Remove beef from cooking liquid and place on cutting board.
Bring remaining liquid in pot to boil for about 20 minutes or until reduced to about half. Whisk together cornstarch and 2 tbsp of water. Whisk into sauce until thickened.
Slice beef. Ladle sauce into shallow bowls and layer meat into sauce. Sprinkle with green onion and orange zest to serve.