This rich and earthy appetizer is the perfect starter before any big holiday meal or add it to your party's hors d'oeuvre table. This creamy vegetable dip is not heavy or filling but it will definitely keep your guests coming back for more. Just a thought, you might want to make a double batch!
Pour water into a medium saucepan to a depth of 1/4"; add cauliflower and garlic. Cover, bring to a boil over high heat, and cook until florets are very easily pierced with a paring knife, about 10 minutes. Drain and set aside.
Meanwhile, heat 2 Tbsp. oil in a large skillet over medium. Add onion, cumin, and 1 tsp. salt and cook, stirring often, until onion is translucent, about 3 minutes. Increase heat to medium-high and cook, stirring often, until onion is golden brown, about 5 minutes more.
Transfer onion mixture to a blender. Add yogurt, lemon zest and juice, cauliflower, and remaining 1 tsp. salt and purée until smooth. With the motor running, add 2 Tbsp. oil in a steady stream until well combined. If dip is too thick, blend in 1 Tbsp. water at a time to reach desired consistency. Let cool to room temperature.
To serve, spread dip in a wide bowl or platter. Drizzle with oil and top with parsley. Serve with romaine hearts, endive leaves, celery, crackers, or pita triangles alongside for dipping.