In a pot, combine onion, orange marmalade, ketchup, white vinegar, garlic, 1/2 teaspoon Montreal seasoning, and Chinese five spice powder.
Cook over medium-low heat, stirring occasionally, until thickened, about 30 minutes.
Reserve 1/4 cup of the glaze and set aside.
Preheat oven to 400°F.
Sprinkle wings with remaining 1 1/2 teaspoons Montreal seasoning.
Arrange wings in a single layer on a jellyroll pan.
Bake for 30 minutes.
Turn wings over and brush with the reserved glaze.
Bake for an additional 15 minutes, then turn wings over again.
Heat broiler and broil wings until golden brown, about 5 minutes.
Return remaining glaze to simmer, adding water to thin as necessary for dipping sauce.
Serve wings with the warm glaze, cucumber slices, celery ribs, and ranch dressing.