Πριν μαγειρέψω, μετράω το ρύζι και ζυγίζω το τυρί, γιατί η συνταγή γράφει ακριβώς πόσα γραμμάρια χρειάζονται.

Because Greek is choosing the aorist subjunctive form μαγειρέψω to refer to one whole action: before I cook / before I start cooking.

• μαγειρεύω = present/imperfective, focusing on an ongoing or repeated action
• μαγειρέψω = aorist subjunctive, focusing on the action as a single event

After πριν, Greek very often uses this kind of form when talking about something that has not happened yet but is expected to happen later.

So:

• Πριν μαγειρέψω = Before I cook
• not πριν μαγειρεύω, which does not fit this meaning

In Modern Greek, πριν can be followed directly by the subjunctive-type verb form:

• πριν μαγειρέψω

You may also hear:

• πριν να μαγειρέψω

Both exist, and both are natural to many speakers. The version without να is very common and completely standard.

So a learner should recognize both:

• Πριν μαγειρέψω
• Πριν να μαγειρέψω

Both mean before I cook.

They are related, but not identical.

• μετράω = measure, count
• ζυγίζω = weigh

So:

• μετράω το ρύζι = I measure the rice
• ζυγίζω το τυρί = I weigh the cheese

Greek is making a distinction between two ways of checking quantity:

• by measurement in general
• by weight specifically

In real life, rice might be measured by cup, volume, or amount, while cheese might be weighed. Even if the recipe later mentions grams, this wording is still natural.

Greek uses the definite article much more often than English does.

So Greek naturally says:

• το ρύζι
• το τυρί
• η συνταγή

Even when English might leave the article out, Greek often keeps it, especially with:

• familiar things in the context
• ingredients
• abstract or general references in normal speech

Here, the rice and the cheese are the specific ingredients involved in the recipe, so the articles sound very natural.

This is a very normal Greek way to speak.

Literally, γράφει means writes, but in context it works like English:

• the recipe says
• the recipe states

Greek often uses γράφει for written instructions, labels, signs, and texts.

So:

• η συνταγή γράφει... = the recipe says... / the recipe states...

You could also hear η συνταγή λέει, which is also common.

Because πόσα has to agree with γραμμάρια.

The word πόσος / πόση / πόσο changes form depending on gender and number. Since γραμμάρια is neuter plural, Greek uses:

• πόσα γραμμάρια = how many grams

Compare:

• πόσο τυρί = how much cheese
• πόσα γραμμάρια = how many grams

So Greek is not using one fixed word like English how much/how many. It makes the word agree grammatically with the noun.

Because the grammatical subject is πόσα γραμμάρια = how many grams.

Since γραμμάρια is plural, the verb is plural too:

• πόσα γραμμάρια χρειάζονται = how many grams are needed

If the subject were singular, the verb would be singular:

• πόσο τυρί χρειάζεται = how much cheese is needed

So the verb agrees with γραμμάρια, not with some hidden English-style idea like amount.

Greek present tense can cover both ideas, depending on context.

So:

• μετράω can mean I measure or I am measuring
• ζυγίζω can mean I weigh or I am weighing
• γράφει can mean it says or it is saying in the appropriate context, though says is the natural translation here

In this sentence, the present tense sounds like a habitual or general action:

• Before cooking, I measure the rice and weigh the cheese...

Greek does not need a separate form the way English distinguishes I measure vs I am measuring.

ακριβώς means exactly.

Here it modifies the idea of quantity:

• ακριβώς πόσα γραμμάρια = exactly how many grams

So the meaning is that the recipe gives a precise amount, not just an approximate one.

Its position is natural, but Greek has some flexibility. You could also hear:

• γράφει πόσα ακριβώς γραμμάρια χρειάζονται

That also works, with only a slight difference in emphasis.

Yes. Both are natural.

• η συνταγή γράφει = the recipe writes / says / states
• η συνταγή λέει = the recipe says

The version with γράφει emphasizes that the information is written in the recipe.
The version with λέει is a little more general and conversational.

So both are good Greek.

The commas help separate the clauses clearly.

• Πριν μαγειρέψω, = introductory time clause
• ..., γιατί ... = reason clause introduced by γιατί

So the punctuation makes the sentence easier to read:

1. Before I cook, ...
2. ... because the recipe says ...

In ordinary Greek writing, this punctuation is very normal.

It really has a subject here.

The subject is:

• πόσα γραμμάρια = how many grams

So this is not an impersonal structure like it is necessary. It is a normal verb with a normal subject:

• πόσα γραμμάρια χρειάζονται = how many grams are needed

If you want, you can think of it literally as:

• how many grams are needed

where grams is the thing doing the grammatical job of the subject.