In a large skillet, heat oil over medium heat; fry mushrooms, onion and garlic, stirring occasionally, until tender and liquid is evaporated, 6 or 7 minutes.
Stir in sun-dried tomatoes, paprika, salt and pepper. Remove from heat; let cool for 10 minutes.
Scrape mushroom mixture into food processor. Add eggs and cheese; blend until fairly smooth. Add lentils and walnuts; pulse until combined, stopping to scrape sides once or twice.
Transfer mixture to bowl; stir in bread crumbs. Refrigerate mixture until chilled, about 1 hour.
Mist a large rimmed baking sheet with cooking spray. Roll mixture into 36 (1-inch/2.5 cm) round balls. Place 1 inch (2.5 cm) apart on a prepared baking sheet.
Recipe Notes
Per Serving: 287 calories, 15 g protein, 14 g fat (3 g saturated fat), 29 g carbohydrates, 7 g fibre, 75 mg cholesterol, 320 mg sodium