In the early time in the game, 20 turn at max, there is the Herbalist Hut to appear!
Its basic use is to cure your party from wounds and/or poison against a challenge (Sneak or hunting, i think), at the cost of 30 of food and 5 of wood! Also, it randomly give 8HP blessing (it can double HP of some character at the begining of the game)! At the begining of the game, it's really helpful.

But there is a way to use it to boost your characters thanks to it!

-You can do it almost as much you want in one turn, the only limit is your ressources
-It raise 2XP if you win the challenge, so it can be use to pass lvl cap for you characters... at the begining, it's less than 20 needed, so a few time and you get a level up!
-The blessing of vitality is stackable, so when you have the blessing for 100 turn or above, you're fine for a while

What i recommend... if you want to use it:

1- Just focus the few first turns in the village for food and wood
2- Try to cook, it will give you more food, and it's lighter
3- When the Hut appear, take everyone with food/wood at 6/1 ratio
4- Do with everyone the Healing Wound challenge
5- Go back and do it again if you need to upgrade your characters more

You can easily boost 3/4 lvl before even uncountering any monsters at the begining, so it's a really good way to make a good start.
I use this even at endgame, you have too much food and wood, i make a use of it, a little boost in HP is not bad, but to finish you XP bar, it is also useful!