Preheat your oven to 425°F (220°C).
In a roasting pan large enough to hold all the chicken pieces in a single layer, whisk the vinegar, olive oil, water, garlic, salt, and pepper together. Add the chicken pieces, sweet potatoes, and dates.
Use your hands to mix everything together and get the mixture on all of the chicken, sweet potatoes, and dates. Move everything around so the sweet potatoes and dates are in a single layer at the bottom of the pan and the chicken is in a single layer on top, skin side up.
Roast until the sweet potatoes are tender and the chicken pieces are firm to the touch and their exposed skin is nicely browned, about 1 hour. Let the chicken rest at room temperature for at least 15 minutes before serving.
Serve the chicken straight from the roasting pan, including a spoon so you can spoon some pan juices over the top, or transfer the chicken, sweet potatoes, and dates to a platter and pour the cooking juices over the top. Sprinkle with the herbs and serve warm.