1Five days before you want to make the crackers, start to make the sourdough base. In a crystal jar, add 50 grams of flour, 50 grams of water, the lemon juice, and the raisins. Mix well, add the lid only halfway on so gases can escape, and let sit overnight. The next day you should see bubbles.
2On day 2, add 50 grams more of flour and 50 grams more of water. Stir the mixture again and let sit another 24 hours. You should see more bubbles and some liquid on top. Drain off the liquid.
3On day 3, throw away half of the jar’s contents. Add another 100 grams flour and 100 grams water. Mix well and let sit another 24 hours. The next day the mixture should look spongy.
4On day 4, throw away everything but 100 grams of the jar’s contents. Add 100 grams flour and 100 grams water, then mix well and let sit another 24 hours. You should notice the smell of the dough has changed. You can now remove the raisins.
5On day 5, throw away everything but 100 grams of the jar’s contents. Add 100 grams flour and 100 grams water, mix well, and let sit until doubled in volume, which may take less than 24 hours.
6Once it has doubled, take 30 grams out to use for the crackers.
7In a bowl, mix together the whole milk, water, honey, 30 grams sourdough base, rye flour, wheat flour, salt, baking soda, and caraway seeds. Knead lightly, form a ball, cover with a cloth, and let sit overnight, unrefrigerated.
8On day 6, preheat the oven to 210 degrees Celsius.
9Pinch off balls of dough approximately the size of a tennis ball. On a lightly floured work surface, roll the dough out flat and very thin. Pierce all over with the tines of a fork so the cracker does not rise in the oven.
10Baste the top of the dough with water and sprinkle on caraway seeds.
11Place the dough on a baking tray or pizza stone and bake for 7 to 10 minutes until golden around the edges.
12Remove to a baking rack to cool before serving.