Place lentils into a large container and cover with several inches of cool water; soak for 2 hours.
Place lentils, tofu, spinach, sugar, 1/2 teaspoon salt, and pepper in a bowl; mix by hand. Incorporate flour until just combined.
Heat vegetable oil in a saucepan over medium heat. Drop rounded teaspoonfuls of the tofu mixture gently into the hot oil. Fry until golden brown, about 2 minutes per side. Drain on a paper towel-lined plate.
Combine sunflower seed oil, soy milk, apple cider vinegar, and sea salt in a bowl; blend with an immersion blender until mayonnaise is smooth. Serve with tofu bites.