Learn Hardcore Spanish (Latin America): Después de cenar, lavo los platos con detergente y una esponja. - After dinner, I wash the dishes with detergent and a sponge.

In Spanish, a preposition (like de) must be followed by a noun or an infinitive, not a conjugated verb or a gerund. So you use después de + infinitive: después de cenar. If you want a noun, you can say después de la cena. The form después de cenando is incorrect.

Do I need the de after después?

Yes, when it’s followed by a noun or an infinitive: después de cenar, después de la cena. If you use a full clause, you use después de que (or, in much of Latin America, simply después que): Después de que ceno… / Después de que cene…

Can I also say Después de la cena or Después de que ceno/cene? What’s the difference?

Después de la cena uses a noun; it’s neutral and common.
Después de que ceno (indicative) talks about a habitual action.
Después de que cene (subjunctive) is used when the action is in the future or not yet realized: Después de que cene, lavaré los platos.
In Latin America, después que is also widely used and correct.

Why is yo omitted before lavo?

Spanish is a pro‑drop language. The verb ending in lavo already shows the subject is “I.” You add yo only for emphasis or contrast: Yo lavo los platos, no tú.

Should it be me lavo los platos since I’m doing the washing?

No. Lavarse is reflexive when you wash yourself: Me lavo las manos. When you wash an object, you use non‑reflexive lavar: Lavo los platos.

Does lavo here mean I’m doing it right now or that I usually do it?

With the time phrase Después de cenar, the simple present lavo most naturally expresses a routine/habit. To talk about a specific future plan, use voy a lavar or a future form: Después de cenar, voy a lavar/los lavaré.

Why is it los platos and not just platos?

Lavar los platos refers to “the dishes” from the meal (a specific, understood set).
Lavar platos (no article) is used for the activity in general or as a job: Odio lavar platos; Trabajo lavando platos.

Does platos mean plates specifically or dishes in general?

Literally it’s “plates,” but in many places los platos idiomatically means “the dishes.” Regional alternatives you’ll hear include los trastes (Mexico/Central America), la loza, or la vajilla.

Why is there no article before detergente but there is una before esponja?

Detergente is a mass/uncountable noun here, so no article is needed: con detergente (“with detergent/soap”).
Esponja is a countable item, so una esponja (“a sponge”). If you mean a specific product, use the article: con el detergente azul. You can also say un detergente to mean “a (type/bottle of) detergent.”

Is con the right preposition for tools? Could I say usando?

Yes. Con marks the instrument: lavo… con detergente y una esponja. You can also say usando: Lavo los platos usando detergente y una esponja. Repeating con before each item is optional: con detergente y (con) una esponja.

Are there regional vocabulary alternatives for detergente, esponja, and platos?

Detergente, jabón para platos, lavaplatos (líquido) are all used; lavavajillas is more Peninsular.
Esponja is common; you’ll also hear fibra (scouring pad) or estropajo (more Spain; in Mexico estropajo can be a natural scrub like a loofah).
Platos vs trastes (Mexico/Central America) vs loza/vajilla (tableware).

What about fregar? I’ve heard friego los platos.

In Spain, fregar los platos is very common for “to do the dishes.” In much of Latin America, lavar los platos is preferred; fregar may mean “to scrub” or colloquially “to annoy.” If you’re aiming for Latin American usage, stick with lavar for dishes.

Is the comma after Después de cenar necessary?

When an adverbial phrase comes first, Spanish typically uses a comma: Después de cenar, lavo… If you move the phrase to the end, no comma: Lavo los platos después de cenar.

Is los in los platos an article or a pronoun? How would I replace los platos with a pronoun?

Here los is the definite article. If you replace los platos with a pronoun, it goes before the verb: Después de cenar, los lavo con detergente y una esponja. After an infinitive/gerund/affirmative command, it can attach: después de cenar, lavarlos; ¡Lávalos!

Any quick pronunciation tips for this sentence?

Después: stress the last syllable (hence the accent): des‑PUÉS.
Detergente: the g before e sounds like Spanish j (a harsh h), so de‑ter‑HEN‑te (the exact sound varies by region).
Lavo: Spanish v sounds like a soft b between vowels: LA‑bo.
Esponja: the j is the same harsh h sound: es‑PON‑ha.