In a medium mixing bowl, combine the Impossible Burger, onion, garlic, salt, and pepper, gently mixing to combine. Cover and refrigerate for 2 hours.
Gently shape the mixture into sixteen 3-inch long sausages, arranging the sausages on a sheet pan. Cover and refrigerate for 1 hour.
Heat a grill, stovetop grill, or skillet over medium-high heat. Cook the sausages, turning occasionally, until browned and cooked through, 6 to 8 minutes.
Serve hot, with toothpicks and ajvar sauce if you like.