Here’s a bright idea: Add zest to your cooking with citrus.
Preheat the oven to 425°. Slice 2 lemons into 1/4-inch-thick rounds; discard the seeds. Squeeze 1/2 cup juice from the remaining lemons.
In a medium saucepan, add the lemon rounds and juice, the kosher salt and 1/4 cup water. Bring to a boil over high, stirring until the salt dissolves. Cover and simmer over low until the lemon rounds are tender, about 10 minutes; drain. Coarsely chop; transfer to a small bowl.
In a small skillet, heat the coriander and cumin over medium, shaking often, until lightly toasted and fragrant, about 1 minute; let cool. Wrap the toasted spices in heavy-duty foil or place in a ziptop freezer bag; crush with a rolling pin.
On a large, rimmed baking sheet, toss the cauliflower, oil, garlic and crushed spices; season with salt and pepper. Arrange in a single layer; roast until the cauliflower is browned in spots, about 18 minutes. Stir in the olives and half the lemon mixture, adding moreif desired; top with the parsley.