I think you cant unless the recipe caps out at 30 you always get the highest possible version
@Mister
Mister Volcano lvl50 Tank SA/FM
Silver Sight lvl 50 Controller Mind/Kin
Cryogenic lvl 50 Tank Ice/Stone
Winters Night lvl 50 Corrupter Ice/Dark
Chaos Agent lvl50 Brute EM/EA
If you select a specific recipe, like say LotG: +Recharge, you get that at the level selected by the slider. But when you random rolls the recipe always drops at highest possible level (assuming you are level 50 ofc). So if you roll in the 35-39 range you will get level 50 recipe if the recipe can drop at level 50, or level 40 if the recipe caps at that level.
Do any recipes cap at a strange level like 41?
dunno! maybe just a glitch. Come think of it, might've been 40.
but cheers for info 
Ok i think i'm seriously dense or something, but i cannot figure these out.
I move the level slider to 30.
I pick from the 26-29 pool.
And the recepie i get is level 41.
Note, char is lvl 50.
How am i sposed to get a lvl 30 recepie?