Soak the lentils. Add the dry green lentils to a bowl, cover them with water, and let them soak for about 8 hours. Once soaked, drain the soaking water and rinse the lentils.
Sprout the lentils (optional). Transfer the soaked lentils into a strainer and set the strainer over a large bowl so any excess water can drain. If you’re using a sprouting jar, invert it into a large bowl or another object that allows it to sit at an angle. This lets water drain constantly. The lentils must stay moist but shouldn’t sit in water. Rinse the lentils every 12 hours. After 24-36 hours, sprouts should start to emerge. If there are no sprouts, drain, rinse, and leave again for a few more hours. While sprouting is not necessary, it does boost fermentation activity.
Process. Add the sprouted (or just soaked) lentils to a food processor together with the chickpea flour, psyllium husk, hemp hearts, baking soda, lemon juice, salt, and water, and process until a dough forms. The reaction baking soda creates upon contact with acid is immediate, so don’t let the dough rest and work as quickly as possible before all the bubbles dissipate.
Bake. Transfer the dough into a parchment paper-lined 8 x 4 inch/20 x 10 cm loaf pan, smooth the top with a spatula, and bake the bread at 380°F/193°C until crispy and golden brown, for about 50 minutes.
Cool. Transfer the bread onto a cooling rack and let it cool completely before slicing.
Store. Wrap the bread in a large tea towel (so it can breathe) and store it in a cool place for up to 3 days. For longer-term storage, slice the bread first and then transfer individual slices into an airtight bag, one on top of the other, in an alternating 90-degree pattern, and press out as much air as possible. Freeze for up to 3 months.