For the Chicken: Pull out and discard the lump of fat and giblets from the main cavity in the chicken; reserve the liver for chicken liver crostini (link). Rinse the chicken inside and out and pat very dry with paper or kitchen towels. Starting at the edge of the main cavity, slide a finger under the skin over each breast, making pockets. Place the salt in a small bowl, mix in the paprika, cumin, pepper flakes, cinnamon and freshly ground pepper. Grate the rind from the lemon (reserve the lemon) and mix it into the spices. Gradually mix in the olive oil. Spread a little of the spice mixture inside the main cavity, and under the skin over the breasts, rub most of the mixture all over the outside of the chicken. Cut the lemon into quarters, and insert as many pieces as will fit into the main cavity. Place the chicken in the center of a large, heavy, rimmed baking sheet, and let stand at room temperature 1 to 2 hours. (The chicken will be delicious even if you don’t have time to let it stand before roasting.)
Position a rack in the center of the oven and preheat the oven to 450 F. Place the chicken in the oven and roast for 30 minutes.
Meanwhile, prepare the vegetables: Cut the cauliflower into 1-inch florets, discarding the heavy center stem. Cut the yams in half widthwise; quarter each piece lengthwise, forming wedges. Peel the onion, cut in half then cut each half into 4 wedges. Place the vegetables in a large bowl. Add the oil and toss to coat. Add the spices and toss to coat.
After the chicken has roasted 30 minutes, carefully remove the chicken from the oven. Tilt the baking sheet and spoon off most of the fat. Arrange the chicken in the center of the pan and spoon the vegetables around the chicken. Return the pan to the center of the oven, and continue roasting until a chicken thigh moves easily when jiggled and an instant read thermometer inserted into the thickest part of a thigh registers 165 F, about 40 minutes longer. If the chicken is getting too dark, reduce the temperature to 425 F. Let the chicken reset 10 minutes before carving. Carve the chicken and serve with the vegetables.
Enjoying leftovers: When cleaning up, reserve any juices in the roasting pan, to add flavor to the dishes you might make with the leftovers. This chicken is as tasty and succulent cold the next day. It is fabulous simply sliced, in chicken sandwiches, or try the Chicken, Sweet potato Fricassee (coming tomorrow) or the Chicken, polenta soup.