Bread recipe

Dry:

• 1 kg wholemeal flour (or plain flour or mixes thereof, whatever you like)
• 4 teaspoons baking soda
• 2 teaspoons salt
• 100 g raisins
• 25 g cinnamon

Wet:

• ~1/2 litre of apple juice
• 4 teaspoons of vinegar.

1. Mix the solids together.
2. Preheat oven to 200°C.
3. Add the vinegar to the apple juice.
4. Roll in juice gradually until all of the flour mix is wetted, but not slimy looking sludge. 
5. Throw a quarter of the mix onto a section of baking paper. 
6. Roll the baking paper up so that it's a crude looking cylinder.
7. Place it on the tray in a way that it wont unroll while the dough bakes.  

For me, this is enough for 4 loaves of bread.

I use a fork and bowel to mix it all together - it spares me losing the sticky dough on my hands.

Now, what is nice about the baking paper is that it helps lock in the carbon dioxide that is going to be generated while it bakes. Which is critical for maximum fluffiness. You end up with two rough looking ends because they are exposed, and a smooth curved surface, where the baking paper touches the dough.

Cooking time:
Until it is visibly steaming (when you open the oven door and steam rolls out and it smells deliciously edible). Essentially, the perfect time is when most of the water has been boiled off, that the loaf is almost dry. Something like 20-30 minutes.

You can keep the dry mix for a couple of days, but once you add the liquid and mix it up, the dough has to go into the oven quickly (<5mins). Otherwise more of the carbon dioxide will be released during baking.

Alternative options:

Instead of baking soda/vinegar: try 8 teaspoons of baking powder; 4 teaspoons of baking soda with 4 teaspoons of cream of tartar; use buttermilk instead of the vinegar and apple juice (roughly 1/2 litre until the dough is damp), any other juice, lemon juice in water (say half a lemon to 1/2 litre of water), use normal milk with the vinegar (either add immediately or let it stand for an hour [as an engineer I would prefer to stir it in this time just to have a consistent and faster souring] while to make your own buttermilk).

Add in about 80 g of finely diced fresh ginger - the raisins and the tart ginger provide a fantastic flavour where they complement each other - I haven't used powdered ginger yet.

Dry some fruits yourself. 4-5 apples cut into small chips (wet size ~1-2 x 1-2 cm) are enough for this amount of dough (150 g or so when dry). Dry in the oven at 140°C with the door open a crack and, if possible a fan blowing across it. Dry until crispy, but not burned, . The apples lose a serious amount of moisture in the drying process (about 60-66% of their wet mass). In my oven it takes about 3 hours for this, but keep going until they are crispy and don't smell burnt or taste like carbon. I generally peel them beforehand. I am partial to pink ladies for this. I haven't used cooking apples yet, and I'm not inclined to.

Add some oatmeal, nuts, shredded All Bran and/or a bit of sugar if you like (you could drop large sugar crystals on the baking paper before you throw the dough on it and roll it up.

Much like my cookie recipe, beyond the bare bones recipe (flour, source of carbon dioxide [baking soda/vinegar, etc.], and a source of water to dampen the dough), you can do what ever you like with it.

Experiment  and see what works best for you.

As a parting thought:
Is carbon dioxide generation critical, or just the simplest/most convenient one to do?

As long as the by-products aren't toxic and are tasty, any reaction that produces a gas could do the job. Although... something heavy like carbon dioxide is probably best because it has a lower diffusivity than something like nitrogen. So it is more likely to stay in the dough.

I wonder what would happen if you had an oxygen or hydrogen producing reaction in there...