Rinse the dry lentils thoroughly under cold water and combine with water in a pot. Bring to a boil, then reduce heat to a simmer, cover, and cook for 20-25 minutes until tender but still holding shape. Drain any excess water and set aside.
While the lentils cook, dice the onion finely and mince the garlic. In a large skillet, heat the olive oil over medium heat until shimmering. Add the diced onion and sauté for about 5 minutes, until translucent and fragrant, with a slight sizzle.
Add the minced garlic to the skillet and cook for 30 seconds until aromatic. Stir in the tomato paste and cook for 1-2 minutes, allowing it to deepen in color and smell. Sprinkle in the smoked paprika, chili powder, and a pinch of cumin, stirring constantly to toast the spices for about 30 seconds.
Add the cooked lentils to the skillet, breaking some with the back of your spoon to mash slightly. Pour in the Worcestershire sauce and tomato sauce, stirring to combine everything into a thick, chunky mixture. Reduce heat to low and simmer for 10 minutes, stirring occasionally, until flavors meld and sauce thickens.
While the filling simmers, split your burger buns and toast them lightly in a toaster or oven at 180°C (356°F) for about 2-3 minutes, until golden and just crispy on the cut side.
Once the lentil filling is thick and flavorful, spoon a generous amount onto the toasted buns. Feel free to add optional toppings like pickles, shredded cheese, or hot sauce for extra flavor. Serve immediately while messy and hot.
