In a small pan, heat olive oil. Add fennel and pepper and sauté for 2 to 3 minutes until tender.
In a large bowl add chicken, egg, cornmeal, sautéed fennel and pepper, herbs, mustard, lemon, pepper and salt. Mix together just so ingredients are combined. Be careful not to over-mix the meat (This will affect the texture and make them very mushy and soft inside).
Gently form the meat mix into eight equal size patties. Make a small dip in the center of the burger to help it not puff up in the middle during cooking. Tip: Use a scale to weigh out the patties so they will be the same size. This will help to avoid over- or undercooking them.
Place in a plastic container with wax paper in between patties and refrigerate for a minimum of 1 hour or up to 2 days.
Start at a high heat to make grill marks on the burger and create caramelization of meat. Continue cooking on medium-low heat or indirect heat.
Do not push down on or poke burgers. Leave them alone until they are ready to flip (when the meat releases from the grill on its own). Rotate 180 degrees to finish the crisscross grill marks and then flip once. Finish cooking on the other side the same way.