1. Slice garlic and scallions. Reserve 1 tablespoon scallions for garnish. In a large skillet over medium-low heat, combine olive oil, garlic, and remaining scallions. Saute until tender, about 2 minutes. Add spinach leaves; cover, reduce heat to low, and cook until spinach is just wilted, about 2 minutes. Remove pan from heat, and let the spinach mixture cool.

2. Transfer the cooked spinach to the bowl of a food processor, and process until smooth, about 20 seconds. Add sour cream and the lemon juice to the food processor. Pulse to combine. Add salt and pepper. This dip can be kept in an airtight container in the refrigerator for up to 1 week (refrigerate sliced scallions for garnish as well). To serve, pour dip into bowl, and top with reserved sliced scallions.