Place a lemon in the center of a bundt pan, cut off the top, and stick 2 large rosemary sprigs stem-first into the lemon.
Rinse the chicken with cold water, dab it dry with a paper towel, and carefully place it on the lemon so that it is standing upright with the rosemary sprigs sticking out of the top.
Combine the ingredients for the marinade and brush it over the chicken from top to bottom.
Combine the carrots, red onions, potatoes, rosemary, olive oil, salt, and pepper and spread the vegetables around the chicken in the bundt pan.
Garnish the bundt pan with lemon wedges and a few more sprigs of rosemary.
Transfer the bundt pan to a preheated oven and cook at 350°F for 1 hour.