In a pan, heat oil and cook onions until pink.
Add mushrooms along with salt, paprika and seasoning. Cook until they soften.
Allow the mushroom to cool and come at room temperature.
Add cup of canned beans along with chia seed powder, lentil flour .
Grind it in a food processor for a minute.
Shape into patties and freeze it for 2-3 hours . You may oil your hands to shape these patties as the batter will be sticky.
Preheat the air fryer for 10 mins at 190 deg C | 375 F.
Brush the patties with oil,Air fry for 10-12 mins.
Brush oil again . Flip and air fry further for 4-5 mins.
Assemble the burger with buns,lettuce,cucumber slices,tomato slices and fried onions.
Alternatively, you can also cook the patties on a cast iron griddle with little oil.