
Preheat the oven to 275°F (135°C). Line two 13×18-inch rimmed baking sheets with silicone baking sheets. (Paper will stick. Once you try these you will never go back.)
Combine the dry ingredients. In a large bowl, stir together the sesame seeds, flaxseeds, pumpkin seeds, sunflower seeds, chia seeds, cornstarch, and optional ground coriander.
Prepare the curry mixture. In a separate bowl or large measuring cup, dissolve the Better Than Bouillon in the boiling water. Whisk in the Thai green curry paste until evenly dispersed.
Make the dough. Add the curry-bouillon mixture and canola oil to the dry ingredients. Stir thoroughly until everything is evenly combined.
Let the mixture rest for 10 minutes. This gives the chia and flax time to absorb liquid and allows the mixture to thicken.
Divide between the two prepared baking sheets. Spread the mixture into a thin, even layer on each sheet, leaving a small border around the edges. A damp spatula or small offset spatula works well.
Taste for salt before adding any topping. The curry paste and Better Than Bouillon both contain substantial salt, so additional salt may not be necessary. If desired, sprinkle the tops very lightly with flaky sea salt.
Bake for about 90 minutes, rotating the pans and switching their positions partway through baking if necessary for even browning.
Check for crispness. The knekkebrød should be golden, dry, and crisp throughout. If the centers are still slightly flexible or damp, continue baking in 10–15 minute increments at 275°F.
Cool completely. Let the crackers cool briefly on the baking sheets, then transfer the parchment and crackers to wire racks. They will continue to crisp as they cool.
Break into rustic pieces or cut into squares. Cutting works best when the crackers are still slightly warm.