In a large bowl, combine the grated onion, ground beef, garlic, 3 tbsp. parsley, 1 1/4 tsp. salt and 1/2 tsp. pepper. Quarter the meat mixture, then form each section into 6 football-shaped meatballs. (The meatballs need to be flat enough so that the skewered onions can also make contact with the grill pan.) Thread 3 meatballs onto each of eight 10- or 12-inch skewers, alternating with chunks of onion.
Heat a grill pan over medium-high heat and brush with 1 tbsp. EVOO. Grill the kebabs, turning occasionally, until just cooked through, 8 to 10 minutes.
Meanwhile, in a medium saucepan, cook the couscous according to package directions, using the remaining 1 tbsp. EVOO and 1/2 tsp. salt. Cover and remove from the heat; let stand for 5 minutes before fluffing with a fork. Stir in the tomatoes, almonds, vinegar and remaining 1 tbsp. parsley; season with salt and pepper. Serve with the kebabs.