01 -
Whisk together the mustard, soy sauce, garlic, thyme, rosemary, and ginger in a bowl. Add olive oil slowly, stirring until it turns creamy. Rub this mix all over the lamb and set it fat-side up on a rack in a roasting dish. Leave it at room temp for 2 hours.
02 -
Turn your oven on to 425°F. Lay the onion chunks, lemon slices, and the fresh herbs under the rack in your roasting pan.
03 -
Put the lamb in the oven and roast it for a solid 30 minutes at 425°F.
04 -
Lower the oven to 350°F. Keep roasting the meat until it hits your preferred level: 135°F for medium-rare or 145°F for medium. This should take another 1.5 hours. Pour 2 cups of chicken broth into the pan after one hour, then keep adding more every 30 minutes, as needed.
05 -
Take the lamb out when it's 5 degrees shy of your target temperature. Move it to a cutting board, cover it with some foil, and leave it alone for 20-30 minutes.
06 -
Pour the juices from the pan through a strainer, skimming off most of the fat. Add chicken broth to make 2 cups if necessary. Stir water and flour to make a thick paste. Heat the pan, pour in the wine, and let it boil down to half. Slowly mix in the juices and paste while whisking. Let it simmer for 5-10 minutes as it gets thicker. Add salt and pepper to finish it off.
07 -
Snip off any strings or netting from the lamb. Cut it into pieces and pour gravy over the top when serving.