Hops:
As only very little hop is used and hardly any hop aroma is perceived in the style, you can use whatever hop you find at home. But be careful: Stay below IBU 5 to prevent impeding the lactos.
Boil:
Traditionally Berliner Weisse is not boiled at all. This however was boiled ca. 30 mins to prevent DMS.
Lactos:
I usually grow my own Lactos. I take a hand full of malt and put it in a simple, warm DME wort. To give the lactos a headstart, I usually add a little lactic acid (80%, from Amazon). That way only acidophile microbes will grow in the wort. Keep it in a warm place – I now use a Yoghurt maker to keep the temerature between 25-35°C, but had success with a thermos flask, too. Every morning, I pour away about 1/3 of the wort and replace it with new wort. After one week I stop pouring away and only keep the temperature between 25 and 35°C. As soon as it tastes lemony sour, it's time to brew. Pour the sour wort right into your fermentor at primary fermentation.
Brett:
Berliner Weisse traditionally incorporates Brettannomyces. I got my strain from two bottles of Brewbaker Jahrgangsweisse 2013 – a commercially brewed Craft Berliner Weisse from germany. Fits the style perfectly.
Strawberries:
This Berliner Weisse is aged for about one month on fresh strawberries. I used 500g of mashed Strawberries for ca. 5 liters of beer. Add it in secondary fermentation.