It’s been so hot that instead of working through the sourdough starter that I have by baking, the starter that I remove when refreshing has just been accumulating in the fridge.  Half-way through the third Mason jar or build-up, the idea of a foccacia-inspired quickbread came to mind, since actual foccacia made with leftover starter would have been far too sour for even the crunchiest of palates.  Baking soda neutralizes most of the acid leaving a slight sour tang and nothing more.

The result of the efforts is a showy pan of crunchy on the outside, tender on the inside, veggie-topped flatbread that’s a great accompaniment to salad or soup; it also makes for a savory afternoon snack all on its own.  The variety of seeds and grains provide amazing texture and a pretty speckled effect in addition to protein that keeps you satisfied right through to the next meal.

Yield: an 11″x17″ pan

What you need for the flatbread:

• 5 cups leftover sourdough starter
• 1/2 cup oat bran
• 1/2 cup whole grain flour
• 1/4 cup sunflower seeds
• 1/4 cup sesame seeds
• 1/4 cup chia
• 1/4 flax seeds
• 1/4 cup amaranth
• 1 teaspoon starter
• 1/4 – 1/3 cup (how rich do you want it?) olive oil
• 1-1/4 teaspoon baking soda

What you need for the topping:

• 2 onions, halved and sliced thinly
• 8 oz white button or cremini mushrooms, sliced
• 3 tablespoons olive oil
• 1 tablespoon herbes de Provence (a French blend of herbs that you can find multiple recipes for online, it can also be purchased pre-blended at most gourmet cooking stores)
• 1/2 cup sliced Kalamata olives

What you do:

1. In a large non-reactive glass or ceramic bowl (in a pinch, plastic will work as well…), mix together the starter, salt, seeds, oat bran and flour for the flatbread.  Cover the bowl and set aside to ferment 3 or 4 hours, until almost doubled.  It may seem a bit wet or loose, just give it time, the chia and amaranth will absorb the free liquid and stiffen up the dough.                
2. While the dough is fermenting, heat the olive oil for the topping (3 tablespoons) over medium heat in a large cast-iron (or other non-stick) frypan.  Add the onions and stir and fry until darkened in some areas and tender in other, about 6-8 minutes.
3. Add the sliced mushrooms to the pan and stir and fry some more, until they begin to release their water.  Add the herbes de Provence and continue cooking until the pan is drying out, the mushrooms are browned and beginning to toast on the outside, another 8-10 minutes.
4. Remove the pan from heat, mix in the sliced olive and set aside to cool.
5. As the fermentation draws to a close, preheat the oven to 450F.  Line an 11″x17″ baking sheet with parchment paper or a silpat (silicone) liner.
6. In a small cup, add a tablespoon or two of the oil for the flatbread to the baking soda to form a slurry.  Whisk in the rest of the oil until smooth.
7. Mix the oil-soda blend into the dough until evenly distributed throughout.  Be careful not to overmix.
8. Drop/spoon/plop the dough onto the prepared baking sheet and spread it all out to cover the surface of the pan with a roughly 1″ layer.
9. Evenly scatter the cooled topping mixture on top and press it into the wet dough.  Using your fingers, create dimples about half the depth of the dough, over the entire surface of the flatbread.
10. Bake at 450F for 10 minutes.  Turn the heat down to 375F and bake for another 25 minutes.
11. Remove from the oven, let cool 5-10 minutes in the pan and then transfer to a rack to finish cooling (unless you want softer/soggier crust, in which case, feel free to leave it in the pan.
12. Serve when cool enough to handle.