Pat chicken dry with paper towels. Sprinkle cavity and outside with 1/2 teaspoon black pepper.
Process lemon juice, ginger, garlic, honey, and canola oil in a blender until smooth. Stir in oregano. Rub lemon mixture over chicken, and place, breast side up, on a plate. Refrigerate, uncovered, 4-8 hours or overnight.
Lightly coat a wire rack with cooking spray; place in a roasting pan. Place chicken, breast side up, on rack; let stand at room temperature 30 minutes.
Position an oven rack in the bottom third of oven. Preheat oven to 425°F.
Combine parsnips, carrots, potatoes, onion, olive oil, salt, and pepper; toss to coat. Arrange vegetables on wire rack around chicken.
Bake chicken and vegetables at 425°F, until a thermometer inserted in thickest portion of thigh registers 165°F, and vegetables are tender, about 50 minutes to 1 hour. Let chicken stand 20 minutes before slicing. Garnish with parsley.