I have been keeping notes on what freezes well for about two years, mostly because I got tired of throwing away things I had frozen hopefully and thawed disappointedly.
The received wisdom is roughly half right, and several of the things people say never to freeze are perfectly fine if you handle them correctly.
Why freezing damages things
Worth understanding because it predicts everything else.
Water inside cells expands as it freezes and forms crystals. Those crystals puncture cell walls. When the thing thaws, the ruptured cells release their water, and the structure collapses.
Slow freezing makes big crystals and more damage. Fast freezing makes small ones and less. This is the entire reason commercial freezing produces better results than a domestic freezer.
Which means the things that suffer are the ones with high water content and a structure you care about. Things that are already soft, or already emulsified, or dry, suffer much less.
What freezes better than its reputation
Cooked pulses and dal. Almost no loss. The texture is already soft so there is nothing to ruin. This is the single most useful freezer item in my kitchen.
Browned onion base. Loses a little texture, which does not matter because it is going into a gravy anyway.
Ginger and garlic, whole and unpeeled. Ginger in particular grates beautifully from frozen and is easier to handle than fresh.
Herbs, if you accept they will be for cooking rather than garnish. Chopped into ice cube trays with a little oil works well.
Bread, which people worry about unnecessarily. Frozen the day it is made and toasted from frozen, it is nearly indistinguishable.
Grated cheese, which does not melt quite the same and is fine for cooking.
Chapati and paratha dough, portioned into balls. This surprised me and it works.
What genuinely does not work
Anything with a high water content eaten raw. Cucumber, lettuce, tomato for salad. These become mush and there is no recovery.
Dairy that relies on emulsion. Cream splits, yoghurt separates, soft cheeses go grainy. Some of this can be whisked back for cooking and none of it recovers for eating as-is.
Potato in liquid. Boiled potato in a curry develops a strange grainy, slightly hollow texture. Roast potato is better, mashed potato with enough fat is fine.
Fried food, which loses its crispness entirely and does not get it back.
Eggs in the shell, obviously, and cooked egg white, which becomes rubbery.
The handling matters as much as the item
This is where most freezer disappointment actually comes from.
Cool things before freezing. Putting something warm in raises the temperature of everything around it, causing partial thawing and refreezing of items that were fine.
Freeze flat and thin. A thin package freezes far faster than a block, which means smaller crystals and less damage. It also thaws faster.
Get the air out. Freezer burn is dehydration at the surface caused by air contact, and it is entirely preventable with proper wrapping.
Portion small. Thawing a large block and refreezing the remainder is where most quality is lost, and it is also the practice most likely to cause a food safety problem.
And label everything with what and when. This sounds fussy and it is the difference between a freezer that gets used and a freezer that accumulates.
The thawing half
Underdiscussed and at least as important.
Slow thawing in the fridge produces better texture than fast thawing at room temperature, because the cells reabsorb some of the released water.
Some things are better not thawed at all. Vegetables going into a hot pan, bread going into a toaster, dal going into a pot. Thawing first only gives the water time to run out.
Anything that has released liquid on thawing should be drained rather than cooked in its own water, unless that liquid is part of the dish.
The time limits nobody observes
Frozen food is safe more or less indefinitely and it does not stay good indefinitely.
Quality declines steadily, mostly through slow dehydration and oxidation. Three months is a reasonable working limit for most cooked food, and six for things well wrapped.
The practical approach is a rotation rather than a limit. Things go to the back when new, and I try to eat from the front. This works about seventy percent of the time, which is better than the alternative of finding something unidentifiable from two years ago.
The freezer itself
A final variable that affects everything above.
Domestic freezers vary considerably in how cold they run and how much the temperature fluctuates. A freezer opened frequently, or overfull, or with a failing seal, cycles through partial thawing repeatedly.
Those cycles are what produce large crystals and freezer burn, more than the total time.
A full freezer holds temperature better than an empty one, which is a genuine argument for keeping containers of water in a half-empty freezer. It sounds absurd and it works.