How to Make It
Combine first 3 ingredients in a saucepan over medium-high heat. Bring to a boil, reduce heat to medium-low, partially cover, and simmer 28 minutes or until lentils are softened and liquid is absorbed. Transfer to a bowl; mash with a potato masher.
Heat 1 1/2 tablespoons oil in a large nonstick skillet over medium heat. Add shallots, and sauté 5 minutes or until softened. Add spinach and next 3 ingredients; sauté 3 minutes or until spinach wilts.
Stir together lentil mixture, spinach mixture, breadcrumbs, and pine nuts until well combined. Cover and chill 1 hour.
Press mixture into 6 patties. Heat remaining 1 1/2 tablespoons oil in a nonstick skillet over medium-high heat. Sauté burgers 2 minutes on each side or until well browned.
Spoon about 3 tablespoons Red Onion Jam onto roll bottoms. Top with burgers, blue cheese, arugula, and bun tops.