Eat your vegetables... in your bread
The addition of vegetables to bread has a long history.
Some cultures, at various times through history, added vegetables out of necessity, because they were a cheaper way of adding bulk to bread - rather than just using expensive wheat flour.
In Australia (where I write from) we are blessed with a relative abundance of food, with varying degrees of affordability. However, the addition of vegetables still has a place in bread making - although primarily for flavour, texture, nutrition, visual appeal, and fun.
Here are two ways to incorporate vegetables into a bread dough - whole pieces lightly folded through at the end of mixing and/or as a puree mixed through the dough to become part of the overall ingredients.
Most vegetables are made up of a lot of water, so careful consideration needs to be given to their addition and influence on the dough.
1. Whole pieces
The simplest way to add vegetables to bread is by lightly folding chunks of cooked vegetables through the dough at the end of mixing.
Roasted vegetables seem to mix through best because of the slight "crust" formed during roasting, however steamed or boiled vegetables will work too.
Method: dice vegetables into 2-3cm pieces; oil and season (optional); cook vegetable until cooked, but firm; allow to cool; when dough is fully mixed/kneaded/developed gently fold through vegetables; proceed as normal (OR for softer vegetables, sprinkle cooked vegetables when doing a “stretch and fold” on the dough.)
Ideas: potato, pumpkin and sweet potato are good starting points.
Add at approx. 20% of total dough weight (E.g. 200 grams cooked vegetable for 1kg bread of bread dough.)
Mixing pureeing cooked vegetables through the dough makes the vegetable become part of the bread. This technique contributes delicious flavour, softens the texture due to vegetable starches and may even add a vibrant colour to the dough (e.g. pumpkin or beetroot).
The challenge with this method of vegetable addition is the additional moisture the vegetables will contribute to the dough. Every vegetable and degree of cooking will have a slightly different effect on the dough. This method requires experimenting!
The first time I tried this method, I misjudged/mis-guessed the water by over one-third! It was a paste - I had to add a lot of flour to make it a dough.
Method: cook vegetables until soft (e.g. roast or steam or boil); allow to cool; puree in blender or food processor; add vegetables at the start of mixing with other dough ingredients; adjust water as required; mix/knead/develop dough until normal stage of readiness.
Ideas: pumpkin, potato or beetroot are good starting points.
Add at approx. half of flour weight (e.g. 500 grams cooked vegetable for 1 kg flour) & reduce water by one-third; adjust water as required through mixing and take notes for next time.
UPDATE: seeds are a complimentary addition to vegetable breads. If that interests you, I wrote an easy to read eBook Seedy Sourdough about seeds and bread here.