Burger King sometimes does unexpected but interesting things in its product lineup and the occasional smart promotion. This time the company did something pretty sharp.

Burger King mentioned plans to sell a vegetarian burger: the Impossible Whopper, based on the Impossible Burger, a plant-based burger product that has made a name for itself. The name will be the Impossible Whopper.

The move is very smart in a number of ways (although mentioning this during Monday's earnings call and announcement of missing earnings estimates wasn't sufficiently distracting). Here are some.

Expand the brand image.

Tried-and-true brands face a difficulty. They must remain the same to please customers who expect that experience. And yet, they must change and evolve over time to keep from being boring and predictable. With concerns about health, sustainable eating, and climate change (to which current agricultural production is supposed to be a significant contributor), a plant-based diet is a topic that receives much attention.

By introducing the Impossible Whopper, Burger King does expand its brand image. That includes a sense of being timely, modern, and fashionable. By making use of the Impossible Burger as a part of the foundation, the company leverages the positive press of the product.

Blocking out competitors.

This is a significant change for a burger chain. It's only a surprise that no competing chain (I'm thinking primarily McDonald's here) did not previously do something similar. Now it will be extremely difficult for any of them to do so. Come out with a vegetarian main meal and it sounds as though you're borrowing from Burger King.

In addition, it would seem likely the restaurant company would have negotiated an exclusivity deal with the corporation that makes the Impossible Burger. That would block competing chains from getting access to the same products. To top it all, it seems that Impossible's manufacturing lines have been unable to keep up with the extended demand that Burger King, as well as Red Robin and Qdoba, have created. So even if Carl Jr.'s or another chain wanted to add themselves to the list, there might not be enough to go around.

Bring in new customers.

Another possible outcome is bringing in new customers. Burger King might be able to attract vegetarians individually or as part of a group. I'm not sure how likely this might be, but the potential is there to appear more welcoming and provide vegetarians with another dining outlet. (Although the thought of having even plant-based patties cooking on the same conveyor belt grill as the meat variety might be off-putting.)

Still, overall a good move. Now it's up to McDonald's and other fast food burger establishments to come up with their answer to the Impossible Whopper.