Combine the lentils and water in a medium saucepan and bring to a boil over medium-high heat. Reduce to a simmer and cook until the lentils are tender, 20–25 minutes.
While the lentils cook, toast the walnuts in a dry skillet over medium heat for 5-6 minutes, stirring frequently, until fragrant and lightly browned. Transfer to a plate to cool.
Drain the cooked lentils in a colander or wire mesh strainer and set aside.
In a large skillet, warm the olive oil over medium heat. After 90 seconds when the oil is hot, add the chopped onions and sauté for 6-7 minutes until translucent and lightly golden.
Add the mushrooms and garlic and continue to sauté for 7 minutes until their liquid releases and evaporates
Add the thyme, oregano, black pepper, mustard, wine, and tamari, and cook for 12-14 minutes on medium-high until most of the liquid has reduced and absorbed. Remove from heat and let cool and continue to release steam for 5 minutes.
Transfer the lentils, walnuts, and mushroom mixture to a food processor. Process until the mixture reaches a smooth, spreadable consistency, pausing as needed to scrape down the sides. Adjust seasoning to taste. Refrigerate until ready to serve, optionally garnish with parsley and chives.