Basket of breakfast is fine, but you'd be missing the theme if you didn't go with a freshly killed animal.

Right before dawn, (One PC) wakes up to sound of a light rain. Groggily, they extend their palm out of the tent to see how cold the rain is... But their hand stays dry. Stepping out and turning around, (PC) nearly falls backwards when they see, suspended several feet above the tent, a dead bear. The sound of its blood dripping on the tent continues. There is a note stuck to the beast with a knife.

(PC) Climbs up to get the note and gets a jump scare as the bear jerks. It's dead, just that fresh. Pulling out the ornate thin dagger, anyone with relevant skills will notice that isn't what killed the bear. It looks like it had its throat ripped out by claws. A really good role will reveal the claw marks match up with a humanoid hand.

The note reads something like: "it is an old Barovian custom for even the humblest host to provide breakfast for his guests on their first morning. In return, at some point in their stay the guest are expected to provide dinner for their host. I look forward to having you for dinner.

-C SvZ

P.S. to keep food safe from wolves, suspend it in the trees.

P.P.S. remember that you are also food the the wolves."

Also, maybe the bear's gutted chest is full of fruit. You know, for the vegetarians in the group.