it's typically paler than the Norddeutsche or Düsseldorf Altbiers. Malt-wise it's typically made up of Pilsner malt w/ a good amount of wheat. Michael Jackson notes that it is slightly sour, due to a cellaring of 6 months or so w/ a resident lactic culture (
https://byo.com/stories/item/123-altbier-style-of-the-month); which means, the homebrewer has a few different options concerning souring. i haven't tried pinkus alt yet but it's on my list. with that being said, one may choose to 1) blend 2x2.5 gal batches or any preferred ratio of hybrid ale to sour ale mix using a cultured lacto pack from wyeast or white labs, or simply allowing lacto to naturally grow via a sour mash, 2) 3 stage fermentation: primary (high temp), secondary (low temp), tertiary (add lacto, and reg temp) or 3) doing tertiary w/ steps as 3, 1, then 2.
also, it's probably less bitter than the other versions, thus allowing lacto to grow more; thus, minimal hopping. Ray Daniels cites a Tabernaemontanus as describing beers along the Rheinland in, i think, the 1500's as being of "poor quality" rather sour, using unmalted grains in addition to malted grains, and "noxious herbs." this described beer was probably the prototype of the Münster Alt.
so i guess, in summary, pils malt, wheat malt, unmalted wheat (perhaps no malted wheat?) and a 1/2 oz or so of a noble hop w/ a mixed hybrid yeast/lacto fermentation should put you in the right direction.
