Drain the canned black beans well. Extra liquid can make the burger mixture difficult to shape.
Cooking the mushrooms until most of their moisture has evaporated helps prevent soft or fragile patties.
Chia seed meal or flaxseed meal acts as a binder.
If the mixture feels too wet, add a little extra lentil flour before shaping.
The uncooked patties can be frozen. If cooking them completely frozen, allow approximately 5 additional minutes, checking for doneness rather than relying only on time.