Add the lemon juice, vegetable oil, plain yogurt, garlic, tomato paste, salt, oregano, pepper, allspice, cinnamon, and cardamom into a large plastic bag, then seal and shake the bag to mix. Chop the chicken into 1 - 2 inch pieces and add the chicken to the bag, then refrigerate at least 4 hours.
Preheat an outdoor grill to medium-high heat and lightly oil the grate. Thread the chicken, onions, and pepper onto metal skewers. Cook on preheated grill until the chicken is golden and no longer pink in the center, about 5 minutes each side. Sprinkle the parsley over the skewers.