Make the Meatballs: Preheat the oven to 400 degrees. Place the lentils, bay leaf and water in a saucepan. Bring to a boil over medium-high heat. Reduce to a simmer and cover. Cook until lentils are starting to become tender, about 10 minutes. Drain the lentils, remove the bay leaf and set aside.
Transfer mushrooms to the work bowl of a food processor and pulse until coarsely chopped. Add lentils, oats, parsley, salt, brown sugar, nutmeg, allspice and pepper. Process until mixture is very finely chopped, about 7 or 8 pulses.
Heat oil in a large skillet over medium heat. Add onion and saute until soft and translucent, about 3 minutes. Add lentil and mushroom mixture and cook, stirring frequently, until it starts to dry out and is begins to brown, about 5 minutes. Add white wine and soy sauce and cook until the liquid is nearly evaporated, about 1 minute more. Remove from the heat and transfer the mixture to a large bowl. Set aside until it is just warm to the touch.
Add eggs. Mix until fully combined.
Line 2 rimmed baking sheets with parchment paper. Using a tablespoon measure, transfer spoonfuls of the mixture to the prepared sheet pans. Roll each spoonful into a smooth ball, dampening your hands if necessary to prevent sticking.
Transfer the sheet pans to the oven and bake until the meatballs are browned and firm to the touch, about 25 minutes, switching and rotating the pans halfway through. Set meatballs aside.
Make the Gravy: Melt butter in a 12 inch nonstick skillet over medium heat. Whisk in flour and cook for one minute. Add broth and soy sauce, whisking constantly. Simmer until reduced slightly. Add cream and nutmeg and return to a simmer. Season to taste with salt and pepper.
Add meatballs to gravy and simmer briefly to reheat. Garnish with chopped parsley or chives if desired. Serve with Stirred Lingonberries
(or store bought lingonberry preserves
) and Fresh Pickled Cucumbers