Soak the lentils. Rinse the lentils, then put them in a bowl and cover with 1 cup of the water. Leave for 30 minutes, until softened. Do not drain.

Blend the batter. Preheat the oven to 350 F (180 C). Tip the lentils and their soaking water into a blender, then add the remaining ½ cup water, 2 tbsp of the olive oil, and ¼ tsp of the salt. Blend on high for a full minute into a completely smooth, pourable batter with no visible bits. It should pour like a thin pancake batter; add a splash more water if it is too thick.

Spread thin. Line a large rimmed baking tray with parchment. Pour the batter on and spread or brush it into a thin, even layer right to the edges. The thinner the layer, the crispier the chips.

First bake. Bake for 20 minutes, until the surface is set and dry to the touch. Lift the sheet on its parchment onto a board and cut into triangles with a sharp knife or pizza cutter.

Oil and season. Spread the triangles out, slightly separated, on the parchment. Drizzle with the remaining 1 tbsp oil and scatter over the paprika, garlic powder, rosemary, black pepper, and remaining ½ tsp salt. Toss so every piece is coated.

Second bake. Return to the oven for 12 to 15 minutes, turning the tray halfway and watching the edges so they do not catch, until golden and crisp. They crisp up further as they cool.

Cool and serve. Let the chips cool completely on the tray, they firm up in the last few minutes off the heat. Serve with chipotle mayo, hummus, or any dip of choice.