Place beef in an 8- by 12-inch roasting pan. In a small bowl, mix wine, hoisin sauce, garlic, and coriander; brush evenly over beef. Roast in a 425 degree oven until a meat thermometer inserted in thickest part of roast registers 135 degrees for rare (about 35 minutes; after 25 minutes, check temperature every 5 minutes). During roasting, brush beef 4 times with wine mixture. If pan drippings begin to burn, add 4 to 6 tablespoons water to pan and stir to loosen browned bits. Transfer beef to a board and cover loosely.
Combine any remaining wine mixture and all the pan juices, then measure; add enough broth to make 2 1/2 cups total. Pour broth mixture into roasting pan; bring to a boil stirring to loosen browned bits. Add couscous; return to a boil, stirring. Remove pan from heat, cover tightly with foil, and let stand until liquid is absorbed (about 5 minutes). Stir in peas, onions, and any juices that have accumulated around beef.