Heat a stovetop pressure cooker over medium heat or set an electric cooker to sauté. Add the onion, ginger, and mushrooms and dry sauté for 2 to 3 minutes. Add the lentils, sweet potatoes, and stock.
Lock on the lid. Bring to high pressure; cook for 6 minutes. Let the pressure come down naturally. Carefully remove the lid, tilting it away from you. Transfer the lentil mixture to a large bowl and let stand until cool enough to handle, at least 15 minutes.
Heat the oven to 375°F. Line a baking sheet with parchment paper and spray with cooking spray, if desired; or line the sheet with a silicone baking mat.
When the lentil mixture is cool, mash it with a potato masher or a fork. Stir in the hemp seeds, parsley, cilantro, and curry powder. Stir in the oats. The mixture should come together and form a thick paste; if it is too wet, add brown rice flour by the tablespoon, as necessary.
With wet hands, form into 8 to 10 patties and place on the prepared baking sheet. Bake for 10 minutes. Turn the burgers and bake for another 10 minutes, until they are firm and brown.
Let cool for a few minutes. Serve immediately, refrigerate, or freeze for up to 3 months.