my second attempt was rather a succes.  my hair looks clean!
recipe:
* 3 tbsp baking soda aka sodium bicarbonate
* 1 - 2 tbsp  honey (i had most succes with runny acacia honey, most people seem to use "creamy" honey though)

mix those into a goo, i added a few drops of water since the honey seemed only to get coated with the baking soda.

apply to the hair, it takes some practice to spread it well, doesn't handle at all like shampoo!

rinse
acid rinse to restore pH: diluted ACV or lemon
rinse again.

the original recipe only uses about 2tbsp of baking soda and 1 of honey, i found this isn't enough to spread it everywhere (either they use very big spoons or i have a big head)



note 1: source claims this makes her go over a week between washes where shampoo only lasts 2days. i can't tell you for myself yet.

note 2: this is actually a well known recipe for clarifying (one could also add baking soda to a shampoo).  8)

i think my hair was really programmed to get greasy after two days, whatever way i wash it
i ended up washing my hair only four days later though, i had rinsed my scalp on the third day and my hair strangely looked less greasy on the fourth day than on the third.