It's a bit time consuming but loot every box, barrel, desk, etc, in any dungeon you run. Recipe can show up as loot from enemy npcs also. If you can get to Coldharbor, loot every container in the city. You'll pick up lots of mats, but you'll need those anyway. You can try stealing from containers in other cities, just watch for people and the guards. I wouldn't try pickpocketing regular npcs until you've raised your legerdemain skill up and put some skill points into pickpocketing. You can unload your stolen goods at a fence in any thieves guild for gold.
That's basically how you get provisioning recipes.
(note, you'll find more recipes if you're willing to take a risk and steal them. Doing the Thieves guild and Dark Brotherhood quest lines are really good for this sort of activity.)
"We have found a cave, but I don't think there are warm fires and friendly faces inside."
Best source for targeted level of recipes is doing Provisioning Writs on a character with that passive for Recipe Level.
However, to have any efficiency at this, your best off doing them on several Alts. I was filling in the blanks in my two characters I designated to know all the recipes, and I used 6 Alts moving them up from L1 to L6 on the recipe passives. Even with that, it took me a month or so doing 6 writs a day to get all the Purples and Blues for each tier. Even then, I had to buy some in the guild stores, and this was back before Furniture Recipes diluted the loot tables.
Enjoy the game, life is what you really want to be worried about.
PakKat "Everything was going well, until I died"
Gary Gravestink "I am glad you died, I needed the help"