I have a theory:
What if you could harvest Honor's God Metal using aluminum?
We know that all shards have a God metal which is the physical representation of their investiture
On Roshar there seems to be two dominant magical-"metals". The first is Shard plate and the second is Shard blade.
In addition, there are two shards on Roshar that are likely the cause of these. Between the two, I see that Shardplate is most similar to Cultivation (It grows when you give it investiture) and Shardblade to Honor (You bond it )
The question remains of how can we get it (and eat it)
First off we know that Aluminum "nullifies" the magical properties of a Shardblade.
Therefore, wrapping a Shardblade in Aluminum would leave it as a normal metal sword.
Lastly, we need to cutting off a chunk. We don't know how much of a Shardblades invincibility is from the metal itself. Therefore, without magic properties, it could be soft enough for us to cut it. Or...
To sum up:
Step 1: Wrap a Shardblade in aluminum
Step 2: *Try to break off a chunk
Step 3: Eat and allomantically burn your newly harvested Tanavastium (or whatever you want to call it)