Set a saucepan over a medium heat, add the cumin seeds and dry toast for a minute or two, until they release their oils and scent. Add the sprouts and toss to coat them in the cumin seeds.
Drizzle in a little olive oil (less than a tablespoon) and saute the sprouts quickly, adding two tablespoons of cold water to the pan to steam them a little, too. You can turn up the heat a bit, but watch that they don’t brown or burn. Cook them for only five or six minutes, depending on their size.
Add the rose harissa, honey and lemon juice, stir to coat the sprouts evenly in the sauce, then season to taste with salt and pepper. Add the butter and lemon zest, stir again to coat and serve at once.