Learn Hardcore Russian: Мама варит борщ в большой кастрюле.

Ма́ма — noun, nominative singular, feminine. Lemma: ма́ма.
вари́т — 3rd person singular present of the imperfective verb вари́ть “to boil/cook (by boiling)”.
борщ — noun, accusative singular, masculine inanimate (same form as nominative). Lemma: борщ.
в — preposition “in/at/into,” takes different cases depending on meaning (see below).
большо́й — adjective modifying a feminine noun in the prepositional singular here; lemma: большо́й “big.”
кастрю́ле — noun, prepositional singular of кастрю́ля “pot (cooking pot).”

How do I pronounce the sentence? Any tricky sounds?

Pronunciation (rough guide): Ma-ma va-REET BORSHCH v bal-SHOY kas-TRYU-le.
With stress marks in Russian: Ма́ма вари́т борщ в большо́й кастрю́ле.
Notes:
- щ in борщ is like “shch” or a long soft “sh.”
- ль in большо́й is a soft “l.”
- ю in кастрю́ле is “yu.”

What tense/aspect is вари́т? Does it mean “is cooking” or “cooks”?

Вари́т is present tense, imperfective aspect. It can mean either “is cooking (right now)” or “cooks (habitually).” Context (e.g., adding сейча́с “now” or обы́чно “usually”) clarifies which.

How do I say the future?

Two common options:

Ongoing/repeated future: Ма́ма бу́дет вари́ть борщ… (“Mom will be cooking/ will cook (habitually) borscht…”).
Single, completed future (perfective): Ма́ма свари́т борщ… (“Mom will cook [and finish] the borscht…”).

Why doesn’t борщ change form? Shouldn’t objects take the accusative?

They do. Борщ is masculine and inanimate, and for such nouns the accusative form equals the nominative. That’s why you see борщ (not something like “борща”). If it were animate masculine (e.g., друга “friend”), you’d see a change.

Can I use борща instead of борщ to mean “some borscht”?

Sometimes Russian uses a “partitive” (genitive) to mean “some” with mass nouns (e.g., выпить чаю). With варить, the neutral choice is accusative борщ. Genitive борща tends to sound either colloquial or suggest quantity (“a batch of”) and is more natural with verbs like навари́ть борща (“to cook a (big) batch of borscht”). For everyday neutral style here, stick with борщ.

What case is в большо́й кастрю́ле and why?

Prepositional (also called locative) because it expresses location “in” with no movement. The preposition в governs:

Prepositional for location: в большо́й кастрю́ле (“in a big pot”).
Accusative for motion into: в большу́ю кастрю́лю (“into a big pot”).

So why not в большу́ю кастрю́лю here?

Because that would mean motion into the pot (e.g., “She pours into the big pot”). Cooking “in a pot” is static location, so use prepositional: в большо́й кастрю́ле.

Why is the adjective большо́й shaped that way?

Adjectives agree with the nouns they modify in gender, number, and case. Кастрю́ля is feminine; in the prepositional singular, the feminine form of большо́й is also большо́й (spelled like the masculine nominative, but here it’s feminine prepositional). Pairings with кастрю́ля:

Nom.: больша́я кастрю́ля
Acc. (motion into): в большу́ю кастрю́лю
Prep. (location): в большо́й кастрю́ле

How is вари́ть conjugated? What about the past?

Present (imperfective):

я варю́
ты вари́шь
он/она вари́т
мы вари́м
вы вари́те
они варя́т

Past:

он вари́л
она вари́ла
оно вари́ло
они вари́ли

Perfective partner: свари́ть (same endings; its “present” forms refer to future time: свари́т = “will cook [and finish]”).

What’s the difference between вари́ть and гото́вить?

Вари́ть: to cook by boiling/simmering; used naturally with soups, pasta, porridge, etc. Вари́ть борщ is idiomatic.
Гото́вить: to prepare/cook in general. You can also say Ма́ма гото́вит борщ, which is broader in meaning.

Why are there no articles (“a/the”)?

Russian has no articles. Ма́ма вари́т борщ can mean “Mom is cooking borscht,” “Mom is cooking the borscht,” or “Mom cooks borscht,” depending on context. Likewise, в большо́й кастрю́ле is “in a big pot / in the big pot.”

Can I change the word order? What changes in meaning?

Yes; Russian allows flexible order to manage information structure/emphasis.

Neutral: Ма́ма вари́т борщ в большо́й кастрю́ле.
Location in focus: В большо́й кастрю́ле ма́ма вари́т борщ.
Emphasize who cooks it: Борщ вари́т ма́ма.
Emphasize what she’s cooking: Ма́ма борщ вари́т в большо́й кастрю́ле. All still mean the same core thing; the fronted element is more topical/contrastive.

Is ма́ма the same as “mother”? What about мать?

Ма́ма = “mom,” informal and very common in speech.
Мать = “mother,” formal/literary or can sound harsh in everyday talk. Possessives are often omitted with close relatives if clear from context, so Ма́ма вари́т… often implies “My mom is cooking…”. You can say Моя́ ма́ма вари́т… to make it explicit or contrastive.

When do I use во instead of в?

Use во to ease pronunciation before certain clusters or to avoid repeating в, e.g., во второ́й (“in the second”), во мно́гих места́х, во Вьетна́ме. Here в большо́й is easy to pronounce, so в is correct.