These are ideas that I’ve used and have worked.

1 Tbsp flax ground
3 Tbsp water

1 Tbsp flax ground
2 Tbsp apple sauce
1 ½ Tbsp water

1 Tbsp chia ground (or 1 ½ whole)
3 Tbsp water

1 banana mashed

** I usually add extra of the above to get things to stick nicely…  so if a recipe calls for water for example – I’ll add a bit of applesauce instead of water in a 2:1 ratio-ish ☺ **