You’re at the Tomb of the Moon, the site your father described in his notes. It’s up to you to explore the tomb further. Look at the left. There’s a door that looks like a safe. Take a closer look. There are tiles on the door that need to be put in the right order. It’s a slider puzzle. For more information on how to solve these read here. The difference with standard slider puzzles is that the empty position is in the middle instead of the end.
For those still having trouble with the puzzle here’s the solution (this puzzle isn’t random):
Numbering the tiles from 1 to 9 from left to right from top to bottom: 8, 7, 4, 1, 2, 5, 8, 9, 6, 5, 4, 1, 2, 3, 6, 5, 8, 9, 6, 5.
When the puzzle is finished, press the cross to the top right and then use the tile from your inventory on the door to open it. Inside you find a ROUND THING with two holes in it. Put the round thing on the stone podium in the middle of the room.
Use the stone on the podium to turn it and the holes in the stone now point at the hole in the wall. A beam of light appears through the stone. The round stone behind you will open revealing a chamber. Out comes the salad….
Game source: A copy of the game was found here on the internet.