A la ensalada le pongo un puñado de nueces.

Yes, they both point to the same thing, but this is very normal in Spanish.

• a la ensalada names the recipient clearly.
• le repeats that idea as an indirect object pronoun.

This kind of doubling is extremely common in Spanish, especially with indirect objects.

So:

• Le pongo nueces a la ensalada = I add walnuts to the salad.
• A la ensalada le pongo nueces = As for the salad, I add walnuts to it.

In English we usually do not repeat the object this way, but in Spanish it sounds natural.

Because the salad is the indirect object here, not the direct object.

In poner algo a algo:

• algo = the thing being put → direct object
• a algo = where/to what it is being added → indirect object

Here:

• un puñado de nueces = direct object
• a la ensalada = indirect object

So the pronoun must be le, not la.

Yes, literally poner means to put, but in food contexts it often translates more naturally as:

• to add
• to put in
• to put on

So A la ensalada le pongo un puñado de nueces is very naturally understood as:

• I add a handful of walnuts to the salad
• or I put a handful of walnuts in the salad

Spanish often uses poner where English prefers add.

Because with poner, Spanish often uses a for the destination or recipient of what is being added.

• Poner algo a un plato
• Poner sal a la sopa
• Poner azúcar al café

This does not always match English word-for-word. English might say in the salad, but Spanish commonly says a la ensalada with this verb.

If you said en la ensalada, it could be understood physically as in the salad, but with poner and food preparation, a la ensalada is the more idiomatic structure.

Starting with A la ensalada gives it more emphasis or makes it the topic.

It is a bit like saying:

• As for the salad, I add a handful of walnuts
• To the salad, I add a handful of walnuts

This word order is common in Spanish when the speaker wants to highlight the thing being talked about.

All of these are possible:

• A la ensalada le pongo un puñado de nueces
• Le pongo un puñado de nueces a la ensalada
• Pongo un puñado de nueces a la ensalada

The version you were given sounds natural and slightly topicalized.

Because Spanish usually omits subject pronouns when they are not needed.

The verb pongo already tells you the subject is I.

• pongo = I put / I add

So yo is unnecessary unless you want emphasis or contrast:

• Yo pongo nueces, pero él pone almendras.

In normal speech, dropping yo is more natural.

Un puñado de literally means a handful of.

It is a very common expression for an approximate quantity, especially with food:

• un puñado de nueces = a handful of walnuts
• un puñado de arroz = a handful of rice
• un puñado de garbanzos = a handful of chickpeas

It does not usually mean an exact measured amount. It just gives a practical, everyday quantity.

After expressions of quantity like un puñado, Spanish normally uses de + noun.

So:

• un puñado de nueces
• un kilo de tomates
• una taza de café

That is just the standard structure.

Why not de las nueces? Because here you mean walnuts in a general sense, not some specific walnuts already identified. If you said de las nueces, it would sound like you mean the walnuts in particular.

Usually nueces most directly means walnuts.

That is important, because English speakers sometimes assume it means nuts in general. In many contexts, it specifically means walnuts.

If you want to talk about nuts more generally, Spanish might use:

• frutos secos = nuts / dried fruits, depending on context
• specific nut names like almendras (almonds), avellanas (hazelnuts), cacahuetes (peanuts)

So this sentence most naturally means a handful of walnuts.

Yes, often you could.

• A la ensalada le pongo un puñado de nueces
• A la ensalada le echo un puñado de nueces

Both can sound natural.

Very roughly:

• poner = to put / add
• echar = to throw in / add / pour in

In cooking and everyday speech, echar is extremely common in Spain for adding ingredients. Poner is also perfectly normal here.

Because the sentence is probably referring to a specific salad already known in the situation.

• la ensalada = the salad

In recipes, cooking instructions, or a meal context, Spanish often uses the definite article when the item is understood.

If you said a una ensalada, it would mean to a salad in a more general or less specific way, which is less likely in a sentence like this unless you are describing a type of salad.

It can be either, depending on context.

Pongo is the present tense, and in Spanish the present can mean:

• habitual action: I usually add a handful of walnuts to the salad
• what I’m doing now: I’m adding a handful of walnuts to the salad
• recipe/commentary style: I add a handful of walnuts to the salad

Spanish uses the simple present more broadly than English, so context decides the exact meaning.

Yes. Some natural alternatives are:

• Le pongo un puñado de nueces a la ensalada.
• Pongo un puñado de nueces en la ensalada.
• A la ensalada le echo un puñado de nueces.

They are all understandable, but they are not identical in feel:

• A la ensalada le pongo... = topicalizes the salad
• Le pongo... a la ensalada = very common neutral wording
• ...en la ensalada = emphasizes location more directly
• le echo = very common in cooking/everyday speech in Spain

The original sentence is completely natural.