Bring a large pot to medium-high heat on the stovetop and add the mushrooms, bell pepper, onion, and just a bit of water to prevent sticking. Sauté for about 4 minutes while stirring occasionally, until the onion just starts to become translucent.

Add the garlic to the pot and sauté another 1-2 minutes.

Bring the temperature of the stovetop down to medium. Add the tomato puree, Worcestershire sauce, maple syrup, smoked paprika, and salt to the pot. Give everything a mix until evenly incorporated.

Add your cooked lentils and crushed pineapple to the pot. Mix to evenly incorporate. Allow to cook until everything is heated through, typically about 5-7 minutes.

Once the entire Sloppy Joe mixture is heated through, remove from heat. If the mixture is not as thick as you would like it, you may allow it to cook a few minutes more - just know that the lentils will eventually break down and become a mushier texture if they overcook for too long, so keep an eye on them and remove from heat if you start to notice this happening.

Serve as you'd like on burger buns of your choice! In my house we like to toast the buns first!