Food aggression in foster dog - broke skin

Ive got an 8 month old heeler x who i just picked up yesterday from another foster who was unable to handle her, and felt she was unsafe for her child.

She mentioned the dog being food aggressive, but also called a lot of mundane, arousal behaviour aggressive as well, so I didnt put much stock in that.

No, she was right. The dog is food aggressive.

Shes been fine with meals, I give kibble, but when my partner was saying hello to her for the first time, he put his hands in the crate and pet her through the bars, which was fine until it was like she suddenly remembered she had a high value chew, and with almost zero warning, went for his hand. (Leading up she was accepting pets just fine, some nervousness cause shes unsocialised, and about a second before she bit she grew still - that was all the warning she gave)

Grabbed his hand and began pulling back on it (no head shaking thank god) my partner was very good about it, stayed calm, didnt yank his hand back. Once she let go he took his hand back, and she began charging the crate, continuing to growl and yell at him.

He moved back a little to see if that would help and it did, so i got him to throw a couple high value treats in (not to reward the behaviour but to hopefully show that he wont take anything, but he will add) it surprised her enough he was able to stand up and move away properly without further complaint from her.

About 15 minutes later I let her out and put her on the tether outside, and he got to meet her properly then, and it was like nothing had ever happened, in fact i think she likes him more than me 😂

She did break the skin on his finger, and i wont be surprised if bruising develops.

Obviously we wont be sticking fingers in the crate anymore, but what are the best steps to help her work through this?

Itll be very hard to adopt her out if she cant be considered safe.

We've nicknamed her Newbie cause she acts like shes new to being a dog and existing in the world. (Which she probably is - came from a farm that she roamed as more of a stray than an owned dog)