My recipe farming toon is lvl 13 and he is doing OK at getting lvl 10 recipes and has even popped a couple lvl 15. He still mostly gets lvl 5 but I'd say one-sixth are lvl 10 or lvl 15.
What I havent gotten are any lvl 10 blues.

I started playing March 31. My toon basically ate lvl 5 green food all the way to lvl 20. I was Covenant and Bear Haunch never seemed to drop and I never found Mutton recipes until I was rich and could buy them from guild stores.
I certainly had no problem whatsoever plowing my way through to lvl 20. I did concentrate on getting Exploration gear and scouring each zone. I was always three levels above the quests in both gear and actual level.
The level 10/level 15 problem has been known and acknowledged by ZoS since very early in the game. However since no one actually needs food to complete those zones, there has been no fix.

All my provisioning mules are level 4.
Two of them I made use of the ubiquity of lvl 35 mats my main was finding and they were very easy to level to max. I then respeced them to release the points from Recipe Improvement and started them on other crafts.
One toon was experimental. I acquired all three Plump Worm recipes over time and gave them to him. I then cooked nothing but Plump Worms. I used 150 thin broth, 150 meal and 80 drippings and got all the way to provisioning 38, unlocking the max hireling.
Then that toon turned around and deconstructed his way to Blacksmithing 32 and unlocked max hireling in that skill. This toon has never swung a sword or cast a spell. He got his skill points from teleporting to guildies and running to skyshards. Even if you die at lvl 4, you automatically resurrect on the spot without a soul gem.
He's been one-shotted by skeevers in The Rift. He was once murdered four times in a row on his way to a skyshard. It was hilarious.