NOTICE: Encounter restaurant is permanently closed.
Encounter restaurant is the dome-shaped structure that is synonymous with Los Angeles International airport.
The terminals at LAX are set up in a U-shaped layout. Encounter restaurant is located at the center of the U, surrounded by terminals on three sides. You can walk there from any terminal. You can find their phone number on the Encounter restaurant website to make reservations or get directions on how to get there from your terminal.
You will need to allow time to get through security and walk through the terminal at LAX. So you will realistically need at least a 2 hour layover for this excursion.