07Using olive oil, carefully brush both sides of each slice. You can then season with both the salt and the pepper.08Heat the grill for between 5-10 min.09Set the burners on the grill to low and place the onion on the grill. Cook the onions on the low burner and flip over every 10 min until they are golden brown.10You should stop when the onions are both golden brown and tender, which typically takes 25-40 min.11Heat the grill for between 5-10 min.12You then need to brush some olive oil onto the onion itself, before allowing placing it on the griddle.13Cook the onions and flip every 10 min until they turn golden brown. Be sure to oil the uncooked side of the onion before flipping.