su wo sukosi ireta sarada ha, bataa wo tukatta ryouri yori tabeyasukute suki desu.

Because Japanese uses relative clauses before the noun they describe.

So:

• 酢を少し入れたサラダ = the salad that has a little vinegar added to it
• バターを使った料理 = dishes that use butter / butter-based dishes

In English, we often put this kind of information after the noun:

• a salad with a little vinegar added
• dishes made with butter

In Japanese, the describing part comes before the noun:

• [酢を少し入れた] サラダ
• [バターを使った] 料理

This is extremely common in Japanese.

That を belongs only to the verb 入れた inside the relative clause.

Break it up like this:

• 酢を少し入れた = (someone) added a little vinegar
• サラダ = salad

Together:

• 酢を少し入れたサラダ = salad that has had a little vinegar added

So 酢 is the object of 入れた, and サラダ is the noun being described by that whole clause.

The same thing happens in:

• バターを使った料理

  Here, バター is the object of 使った.

少し means a little / a small amount.

In 酢を少し入れた, it modifies 入れた and tells you how much vinegar was added.

So the sense is:

• added a little vinegar not
• slightly added vinegar in some vague way

A natural English translation is:

• a salad with a little vinegar added

は marks サラダ as the topic of the sentence.

So the sentence is structured like:

• As for salad with a little vinegar added, ...

Then the speaker says two things about it:

1. it is easier to eat than butter-based dishes
2. they like it

So は helps set up this kind of salad as the thing being talked about.

より means than in comparisons.

So:

• バターを使った料理より = than dishes made with butter

It connects to 食べやすい:

• バターを使った料理より食べやすい
• easier to eat than dishes made with butter

So the comparison is mainly about ease of eating.

Grammatically, より most directly goes with 食べやすくて, so the clearest reading is:

• It is easier to eat than dishes made with butter, and I like it.

So the comparison is explicitly attached to 食べやすい.

The sentence does not directly say:

• I like it more than butter dishes

That idea might be implied in context, but the grammar mainly says:

• compared with butter dishes, this salad is easier to eat
• and I like it

食べやすい means easy to eat.

It is made from:

• 食べる = to eat
• やすい = easy to do

So:

• 食べやすい = easy to eat

To connect it to another statement, the -い changes to -くて:

• 食べやすい → 食べやすくて

This -くて form is like saying:

• and
• being...
• because it is... (depending on context)

Here it simply links the ideas:

• It’s easy to eat, and I like it
• more fully: It’s easier to eat than butter dishes, and I like it

It can carry that nuance, yes.

The て-form connection is sometimes just and, but in real usage it can also suggest a reason or background:

• 食べやすくて好きです
  • It’s easy to eat, and I like it
  • or more naturally, I like it because it’s easy to eat

Both are possible. The sentence does not force a hard distinction.

Because 好き is not a verb. It is a na-adjective / adjective-like noun.

So:

• 好きです = I like it / it is liked

This is one of those expressions that works differently from English. Japanese often expresses liking with 好き rather than a verb equivalent to to like.

In this sentence, the thing liked is the topic:

• 酢を少し入れたサラダは ... 好きです
• As for salad with a little vinegar added, I like it

Because Japanese often leaves out subjects when they are obvious from context.

Here, 好きです naturally suggests the speaker’s opinion, so 私 is understood:

• (私は) ... 好きです
• (I) like it

Likewise, the doer in 入れた and 使った is not stated because it is not important. The focus is on the kinds of food, not on who added the vinegar or used the butter.

Here it clearly means vinegar was added to the salad.

That is because:

• 酢を少し入れた = added a little vinegar

Then that clause describes サラダ:

• the salad for which a little vinegar was added

In more natural English:

• a salad with a little vinegar added

Japanese relative clauses can sound more literal if translated word-for-word, so it is better to understand the overall phrase naturally.

Japanese nouns usually do not change form for singular vs. plural.

So 料理 can mean:

• a dish
• dishes
• food
• cooking

Here, because of より and the general comparison, it is most natural as:

• dishes made with butter or
• butter-based food

The same is true for サラダ: Japanese does not need to mark a salad vs. salads unless that distinction matters.

Yes, that is a very close structural translation.

A more natural English version would be something like:

• I like salads with a little vinegar added because they’re easier to eat than dishes made with butter.
• or I like a salad with a little vinegar in it; it’s easier to eat than butter-based dishes.

The Japanese structure is a bit different from natural English, but your literal version reflects the grammar well.

Yes. バターを使った料理 is more explicit and natural for learners to read:

• バターを使った料理 = dishes that use butter

It clearly tells you:

• バター is the ingredient
• 使った describes the dishes

Something like バター料理 is much less standard and can sound less precise. Japanese often prefers this relative-clause style when describing how something is made.

A helpful breakdown is:

• 酢を少し入れたサラダは、
  • As for salad with a little vinegar added,
• バターを使った料理より
  • than dishes made with butter,
• 食べやすくて
  • it is easier to eat, and / because it is easy to eat,
• 好きです。
  • I like it.

So the core idea is:

[Topic] + [comparison] + [description] + [speaker’s opinion]

That is a very common Japanese sentence pattern.