These appetizers have all the flavours of a classic deli sandwhich.
Preheat the oven to 450°F.
Line 2 baking sheets with aluminum foil and coat with cooking spray.
Heat a medium skillet over medium heat and add olive oil to coat. Add the onion and garlic and saute until translucent, about 5 minutes. Remove from the heat and allow to cool until no longer hot to the touch.
Meanwhile, combine the eggs, breadcrumbs and 1/4 cup water in a large bowl. Allow to sit until the breadcrumbs are soaked through, about 5 minutes. Add the onions and garlic, parsley, mustard powder, brown sugar, salt, crushed red pepper, cinnamon, coriander, liquid smoke, allspice, cloves, ginger and some black pepper. Mix to combine, then add the ground beef. Mix until thoroughly combined; I like to use my hands to make sure that everything is evenly incorporated. Form 1 oz balls, a little bigger than 1 inch in diameter, and place on the prepared baking sheets spaced 1 inch apart.
Bake until cooked through and beginning to brown, about 20 minutes. Allow to cool slightly.
Meanwhile, spread rye squares on a baking sheet and bake until lightly toasted, about 5 minutes. Top each toast with a squirt of brown mustard (about 1/2 teaspoon or as desired), 1 meatball and 1 pickle chip. Hold it all together with a toothpick and serve!