Heat the oil over medium heat in a pot or Dutch oven. When the oil is shimmering, add the onion. Sauté the onion for 5-7 minutes, or until the onion is soft and translucent, stirring often. Add the garlic, ginger, cumin, coriander, cinnamon, and allspice. Cook for one minute, stirring constantly.
Add the broth, tomatoes, squash, chickpeas, and raisins. Bring the mixture to a boil. Reduce the heat to low, cover, and cook for 10 minutes. Uncover the pot and cook for 10-15 minutes more, or until the squash is tender and the stew has thickened. Stir in vinegar and adjust salt to taste.
Serve over cooked couscous, quinoa, or bulgur.