In a large skillet, heat the olive oil over medium heat. Add the onions and cook until softened and golden, about 10 minutes. Stir in the mixed nuts and toast until fragrant, 3–4 minutes. Add the dried cranberries and rice, tossing to coat in the oil. Pour in the lemon juice and stir to combine.
Remove the skillet from heat. Fold in the cilantro, mint, date syrup, salt, cinnamon, black pepper, and cloves. Let the mixture cool to room temperature.
Lay a grape leaf on a clean surface, vein side up. Place a teaspoon of filling near the base of the leaf. Fold in the sides and roll tightly into a small cylinder. Repeat with the remaining leaves and filling.
Arrange the stuffed leaves snugly in a large pot, seam-side down, in tight layers. Pour the lemon juice and olive oil over the leaves, then add enough water to just cover them. Place a heatproof plate on top to keep the leaves submerged.
Bring the water to a gentle boil over medium-high heat. Reduce the heat to low, cover, and simmer for 1½ hours, until the leaves are tender and the rice is cooked through. Let cool slightly before serving.
In a small bowl, whisk together the sour cream, dill, salt, pepper, and cumin. Spread the sauce on a serving platter. Arrange the grape leaves on top, and garnish with lemon wedges, pine nuts, and a drizzle of olive oil.