Combine rinsed lentils and vegetable broth in a medium saucepan. Bring to boil, then reduce heat to low, cover, and simmer 20-25 minutes until tender but not mushy. Drain excess liquid thoroughly and set aside to cool.

Heat olive oil in large skillet over medium heat. Add onion and carrot, sauté 6-8 minutes until softened and onion becomes translucent. Add garlic and cook 1-2 minutes until fragrant. Stir in tomato paste and cook 1-2 minutes, stirring constantly. Remove from heat and cool slightly.

Finely chop walnuts or pulse in food processor until they resemble coarse crumbs. For enhanced flavor, lightly toast in a dry pan before chopping.

In large mixing bowl, combine cooled lentils, sautéed vegetable mixture, walnuts, breadcrumbs, Italian seasoning, smoked paprika, parsley, salt, and pepper. Add egg and soy sauce, then mix until just combined. Don't overmix.

Cover mixture and refrigerate 15-30 minutes. Preheat oven to 400°F (200°C) and line baking sheet with parchment paper.

Using slightly damp hands, roll 1.5-2 tablespoons of mixture into firm balls about 1.5 inches in diameter, making 20-24 meatballs.

Bake 20-25 minutes until browned, firm, and slightly crispy outside. Can flip halfway through for even browning.