A barbecue grill and components thereof that allow a user to obtain a controlled burst of high intensity heat for a limited period of time, comprising at least one quick sear burner, a quick sear valve assembly adapted for fluid communication with the quick sear burner, and a cooking surface adapted to be positioned above the quick sear burner in or on a firebox of a barbecue grill. The quick sear valve assembly, in turn, comprises a main valve for normal operation of the quick sear burner, and a bypass valve for high intensity heat output of limited duration. The quick sear valve assembly includes a mechanism that is configured to allow the user to selectively actuate the bypass valve.