غذایی که مادرم با گوشت درست میکند، همیشه خوشمزه است.

که is the relative marker, meaning that / which / who depending on context.

In this sentence, it links غذایی to the description that follows:

• غذایی = food / a dish
• که مادرم با گوشت درست می‌کند = that my mother makes with meat

So the structure is:

• غذایی که... = the food / dish that...

Unlike English, Persian usually keeps که in this kind of relative clause.

The -ی on غذا often gives the noun an indefinite or non-specific feel, so غذایی is something like a food / a dish / the kind of food.

In relative clauses, Persian very often uses this form naturally:

• غذایی که...

Even if English translates it as the food that..., Persian may still use -ی. So you should not always force a literal a in translation.

Without -ی, غذا که... would sound unnatural here.

Because که does not need ezafe before it.

Compare:

• غذای خوشمزه = delicious food
  
  • here you need ezafe: غذایِ
• غذایی که مادرم درست می‌کند = the food that my mother makes
  
  • here the noun is followed directly by که

So a relative clause with که connects directly to the noun.

Because -م is an attached pronoun meaning my.

• مادر = mother
• مادرم = my mother

This is very common in Persian:

• دوستم = my friend
• کتابم = my book
• برادرم = my brother

You could also say مادر من, but مادرم is usually more natural and compact.

Because Persian normally uses Subject–Object/Complement–Verb order, with the verb near the end.

Inside the relative clause, the order is:

• مادرم = my mother
• با گوشت = with meat
• درست می‌کند = makes

So literally, the clause is roughly:

• my mother with meat makes

That is normal Persian word order.

Here درست می‌کند means makes or prepares.

• درست کردن = to make / prepare / fix
• می‌کند is the present habitual/imperfective form of کردن

So:

• درست می‌کند = she makes / she prepares

Because the sentence also has همیشه = always, the meaning is clearly habitual:

• always makes
• not is making right now

می‌کند breaks down like this:

• می- = imperfective/habitual prefix
• کن = present stem of کردن
• -د = third person singular ending

So می‌کند means:

• he/she/it does
• in this sentence, specifically she makes

Since the subject is مادرم, it means my mother makes.

In standard spelling, it is usually written می‌کند with a half-space. You may also see میکند, but می‌کند is the standard form.

با گوشت means with meat, and that is the natural choice here when talking about an ingredient used in a dish.

• با گوشت = with meat / using meat

از گوشت more literally means from meat / out of meat, which is possible in some contexts but sounds less natural for this sentence.

So for food preparation, با + ingredient is often the most natural wording.

Because غذایی is the subject of the main sentence, not a direct object.

Main sentence:

• غذایی که مادرم با گوشت درست می‌کند = the food that my mother makes with meat
• همیشه خوشمزه است = is always delicious

So the whole noun phrase is the thing being described as delicious. Since it is the subject, را is not used.

You would use را if that noun phrase were a direct object, for example:

• غذایی که مادرم با گوشت درست می‌کند را دوست دارم
  = I like the food that my mother makes with meat

Because Persian adjectives do not change for gender or number.

So خوشمزه stays the same whether the noun is singular, plural, masculine, feminine, etc.

Here it is a predicate adjective:

• خوشمزه است = is delicious

This is a very common pattern in Persian:

• هوا خوب است = the weather is good
• این غذا خوشمزه است = this food is delicious

Here همیشه means always, and it modifies the main statement:

• همیشه خوشمزه است = is always delicious

Its position here is very natural.

Word placement in Persian is somewhat flexible, but moving همیشه can slightly change the focus. For example:

• غذایی که مادرم با گوشت درست می‌کند، همیشه خوشمزه است
  = The food my mother makes with meat is always delicious.
• مادرم همیشه با گوشت درست می‌کند
  = My mother always makes it with meat.

So yes, adverbs can move, but their position affects what they seem to modify.

The comma is not absolutely required, but it is helpful.

Because the subject is long:

• غذایی که مادرم با گوشت درست می‌کند

the comma helps separate it from the main predicate:

• همیشه خوشمزه است

So the comma improves readability, especially in writing. In shorter or more casual writing, it may be omitted.

In everyday speech, it would often sound like:

• غذایی که مادرم با گوشت درست می‌کنه، همیشه خوشمزه‌ست.

Common spoken changes:

• می‌کند → می‌کنه
• است → ـه / ـست

So the formal written sentence and the colloquial spoken version mean the same thing, but the spoken one sounds more natural in conversation.