Learn Portuguese (Portugal): Temos amêndoas assadas e as de ontem. - We have roasted almonds and the ones from yesterday.

Here, as acts as a demonstrative pronoun meaning "the ones". It steps in to replace as amêndoas (the almonds) so we don't have to repeat the noun. In Portuguese, the words o, a, os, and as are frequently used this way right before de (of/from) or que (that/which).

Could I use aquelas instead and say aquelas de ontem?

Yes, aquelas de ontem (those from yesterday) is grammatically correct. However, using as de ontem (the ones from yesterday) is much more natural and common in everyday Portuguese unless you are specifically emphasizing or pointing out a distant batch of almonds.

Why does the adjective assadas come after amêndoas instead of before it?

In Portuguese, adjectives that categorize a noun or describe a physical state, like being roasted (assadas), almost always follow the noun. It also takes the feminine plural ending -as to agree with amêndoas.

How does the 's' at the end of Temos sound when followed by amêndoas?