Combine water, lentils, and salt in a saucepan; bring to a boil, reduce heat to medium, and cook until all the water has been absorbed and lentils are nicely cooked, about 20 minutes. Transfer to a large bowl.
Mash lentils with a potato masher; set aside.
Heat 2 tablespoons canola oil in a skillet over medium-high heat. Saute celery and red onion in hot oil until tender, 5 to 7 minutes. Drain and discard excess oil and transfer celery and onion to a bowl.
Stir molasses, ginger, and mustard together in a small bowl; stir into the celery mixture until the celery and onion are evenly coated. Stir celery mixture into the mashed lentils. Shape lentil mixture into 6 patties.
Heat 1 tablespoon canola oil in a skillet over medium heat; fry patties in hot oil hot and firm in the center, 5 to 7 minutes per side.