5 cups broccoli florets (about 12 ounces; see Cook's Note)
One 15-ounce can chickpeas
1 cup roughly chopped fresh parsley leaves and stems
1 cup roughly chopped fresh cilantro leaves and stems
1 tablespoon fresh lemon juice
1 teaspoon ground cumin
1 teaspoon ground coriander
1 teaspoon baking powder
3 cloves garlic
1 small onion, diced
Kosher salt and freshly ground black pepper
3/4 cup panko breadcrumbs
3/4 cup full-fat plain Greek yogurt
1 tablespoon extra-virgin olive oil
3 to 6 teaspoons harissa paste
Olive oil cooking spray, for coating the broccoli balls
Over medium-high heat, add about 1 inch of water to a large skillet and bring to a boil. In a steamer basket, arrange the broccoli florets in a uniform layer. Place the steamer basket over the boiling water and cook for about 8 minutes, or until crisp-tender (depending on the size of the florets). Broccoli should be moved to a big platter to cool slightly.
Paper towels should be used to line a baking sheet. Drain the chickpeas, be careful to save the liquid, and give them a good rinsing with cool water. On the prepared baking sheet, evenly distribute the broccoli florets on one half and the chickpeas on the other. To drain extra liquid, pat the broccoli and chickpeas with additional paper towels.
Add 3 tablespoons of the leftover chickpea liquid to the food processor along with the parsley, cilantro, lemon juice, cumin, coriander, baking powder, garlic, onion, and 1 teaspoon of salt, and a few grinds of pepper. About 30 seconds of pulsing is required to finely chop the ingredients.
Then add the chickpeas and broccoli, and pulse once more, pausing to scrape the sides as necessary, for about two minutes, or until the chickpeas and broccoli are finely chopped. Add the panko after transferring the mixture to a medium bowl. 30 minutes of refrigeration undercover.
In the meantime, combine the yogurt, olive oil, harissa, 2 tablespoons water, 1/2 teaspoon salt, and a few grinds of pepper in a small bowl. The spice level should be according to preference. To cool, refrigerate. Set a wire rack inside a baking sheet and preheat the oven to 375 degrees Fahrenheit.
Form the chickpea-broccoli mixture into 1 1/2-inch ball, each containing about 1 heaping spoonful, using a tablespoon or medium scoop. Place the balls on the wire rack at even spacing and liberally mist with olive oil spray. Bake the balls for about 45 minutes, rotating the baking sheet halfway through, until they are deeply brown and crisp. With the yogurt sauce, serve warm.