Lisa Vanderpump and Kyle Richards are such bitter enemies they’re always looking for new ways to stick to each other — such as Lisa sending her restaurant tab to Kyle’s table.

So, here’s the deal … Lisa and her husband, Ken Todd, hit up the ritzy Shu Restaurant Monday in L.A. … where Kyle also was having dinner with a ‘Housewives’ executive producer.

We’re told Lisa and Ken sat several tables over. Lisa never went to Kyle’s table to say hello … nor did Kyle pay a visit to Lisa’s table — for obvious reasons, we think. But, the EP, who also produces "Vanderpump Rules" and ‘Overserved’ — did notice Lisa and said a quick hello.

Kyle Richards and Lisa Vanderpump Together