Preheat oven to 450°. Halve sweet potatoes lengthwise; cut each half into four long sticks. Brush with 2 tablespoons olive oil. Place skin side down in a 9x13-inch baking dish coated with 1 tablespoon oil. Roast on lower rack for 15–20 minutes, until fork tender.
While potatoes cook, make dip: Mince garlic, green onion, and basil in a food processor. Add tofu, oil, and vinegar. Blend well. Serve with sweet potato sticks.