(5 gallons/19 L, extract with grains)
OG = 1.049  FG = 1.005 IBU = 9  SRM = 4  ABV = 5.9%

Ingredients:

5 lbs. (2.27 kg) wheat dried malt extract
0.5 lb. (0.23 kg) crystal malt (20° L)
0.5 lb. (0.23 kg) cracked wheat malt
2.6 AAU Saaz hop pellets (45 min.) (0.75 oz./21 g at 3.5% alpha acids)
4-5 lbs. (1.8-2.3 kg) fresh sour green apples, chopped
Wyeast 3278 (Belgian Lambic Blend) or White Labs WLP655 (Sour Mix 1) SafAle US-05 (optional)
3/4 cup corn sugar (for priming)

Step by Step:

In 2.5 gals. (9.5 L) of cold water, steep crystal and cracked wheat malt. Bring gradually up to 170 °F (77 °C) and remove the grains. As water comes to a boil, remove briefly from the heat and stir in dry malt extract. Stir until all the extract has dissolved, then return to heat. When the wort begins to boil, add hop pellets and boil 45 minutes. Remove from heat, cool quickly, and add enough chilled, sterile water to make up 5 gals. in your fermenter. When cooled to 75 °F (24 °C),  pitch yeast. [If you want a cleaner style of beer, I recommend pitching a pack of a clean ale yeast such as SafAle US-05 or Lallemand Nottingham yeast at this point and the lambic blend after primary fermentation. For a funkier version, pitch the lambic blend now.] Ferment relatively warm (70 to 75 °F/21 to 24 °C) until the first phase of fermentation is done (three to five days, usually), then rack into a secondary in which you have already placed the chopped apples. If you went the cleaner lambic route, pitch prepared Wyeast 3278, close up, and condition cool (50 to 55 °F/10 to 13 °C) for 10 to 15 days. Prime with corn sugar, bottle (carefully avoiding apple debris as you siphon), and age four to six weeks to allow the flavors to blend well.

Tips For Success:

The cracked wheat malt is placed in the recipe for a specific reason, to provide food for the critters that can digest the wheat flour. This is something normal brewer’s yeast cannot ferment. A traditional way to brew a Lambic ale was to perform a turbid mash which set aside portions of the mash that allowed some starch to get through the mashing process. The cracked wheat is used as a substitute for this recipe This is only an approximation of a lambic style, well within the abilities of the average homebrewer. For a more authentic lambic, which is difficult but usually worth it, please refer to Jean-Xavier Guinard’s Lambic, volume three of the Brewers Publications Classic Beer Style Series.

Fruit: Obviously, apple is not the only fruit possibility here. Whatever you’ve got, try it. In combinations, too. If you have several one-gallon jugs, split a batch into five and try five different fruits, one pound of each.

Hops: Belgian brewers of lambics generally use hops only for their preservative value (and they often use stale, faded hops at that!). No real bitterness or aroma is needed here, although a mild flavoring hop is not out of place.

Yeast: There are plenty of other lambic bacteria cultures on the market. Check with your supplier for his or her recommendation or look around the internet to see what is available.