X17 caught up with Miley Cyrus, 18, and boyfriend Liam Hemsworth, 21, on a romantic dinner date in Studio City Tuesday night!

The on-again, off-again couple grabbed Japanese food at Kiwami by Katsuya, where they dined on the patio and posed with fans for photos.

Liam playfully grabbed Miley's head, then put his arms around her and gave her a big smooch! See it all in our exclusive video above!

Liam reached into his wallet (which was packed with cash -- check out our pics below) to pay for the valet, and the couple drove off in a Mercedes. Maybe heading back to Miley's new $4 million pad?