1/2 cup medium-grain rice, such as Spanish or arborio
2 cups warm water
6 medium zucchini (about 2 1/4 pounds total), ends trimmed
1/4 cup extra-virgin olive oil
1 large sweet onion, coarsely chopped
1 medium fennel bulb, cored and coarsely chopped
1 teaspoon Aleppo pepper (see Note) or pinch of crushed red pepper
1 cup drained canned diced tomatoes
1/3 cup roasted, salted almonds, finely chopped (1 1/2 ounces)
1/4 cup finely chopped dill
1/4 cup finely chopped parsley
1 tablespoon finely chopped mint
Salt and freshly ground pepper
12 brined grape leaves (optional), drained and rinsed
1/2 cup chicken stock
Preheat the oven to 375°. In a medium bowl, soak the rice in the warm water for 20 minutes; drain. Cut each zucchini in half crosswise, making 12 cylinders about 4 inches long. Using a melon baller or small spoon, scoop out the flesh to form cups with a 1/4-inch-thick shell. Coarsely chop the flesh and reserve 3/4 cup. Save the remaining flesh for another use.
In a large skillet, heat 2 tablespoons of the olive oil until shimmering. Add the onion, fennel and reserved 3/4 cup chopped zucchini and cook over moderately high heat, stirring occasionally, until lightly browned, about 10 minutes. Add the Aleppo pepper and cook for 1 minute. Stir in half of the tomatoes, the drained rice, almonds, dill, parsley, mint and 1 1/2 teaspoons of salt and season with pepper.
Using a small spoon, fill the zucchini cups with the rice mixture, mounding it. Transfer the cups to a small cast-iron casserole or large saucepan. Tuck the grape leaves in between the zucchini cups to keep them upright. Spoon the remaining tomatoes on top and pour the stock all around. Drizzle with the remaining 2 tablespoons of olive oil.
Cover and bake for 1 hour and 5 minutes, or until the zucchini and rice are tender. Let the zucchini cool for 15 minutes and discard the grape leaves. Serve the stuffed zucchini warm or at room temperature.
The cooked stuffed zucchini can be refrigerated for up to 2 days.
Aleppo pepper is a mildly hot, coarsely ground red chile with a complex, fruity flavor. It can be mail-ordered from Penzeys Spices (800-741-7787 or penzeys.com).