Peruvian Dishes

The adjective form of Peru is Peruvian. Not all countries have a different adjective form, but Peru does.

I ate Peruvian dishes at today’s lunch.

It was made bywith beef, some vegetables and french fries.

"made by X" -> X is the cook
"made with X" -> X is an ingredient (or multiple ingredients in this case)

It was very delicious and I thought that the taste is acceptable for Japanese people.

There may be a better word than acceptable here, acceptable has a sense of "sufficient" / "just enough", and it comes across as sort of criticising the food as normally people would use stronger phrases for good food.

Maybe "familiar" might be what you're trying to get across here?

I heard that Peru’s food culture is influenced by someother countryies, of course including Japanese.

If it's "including Japan", it's not just Japan, it's other countries + Japan, so countries should be plural here.

Peru haves a wide area, many mountains and wide sea.

A country is usually treated as a singular noun grammatically, unless the name itself is somehow descriptive and plural (like "the United States").

This was a good experience and I’d like to try other dishes.

Peruvian Dishes

I ate Peruvian dishes at today’s lunch.for lunch today

The dish was Lomo sSaltado.

It was made byconsists of beef, some vegetables, and french fries.

It was very delicious, and I thought that the taste is acceptable for Japanese people.

I heard that Peru’s food culture is influenced by some country, of courseies, including Japanese.

Peru haves wide areas, many mountains, and a wide sea.

I guess it makesthey have various dishes.

This was gooda great experience, and I’d like to try other dishes.

Peruvian Dishes

As an adjective describing "dishes", use "Peruvian".

I ate Peruvian dishes at today’s lunch.

The dish was Llomo saltado.

It's not a brand or named after someone, no need to capitalize.

It was made byfrom beef, some vegetables and french fries.

It was very delicious, and I thought that the taste is acceptable for the Japanese.

I heard that Peru’s food culture is influenced by somemany country, of courseies, including Japane of course.

You started with "countr(ies)", so it should be "Japan" and not "Japanese".

Peru have wide area,'s territory is vast. It has many mountains and wide seas.

I guess it makes various dishesthat's why the ingredients are also varied.

This is my best guess at what you wanted to say: because of the mountains and seas, Peruvians have access to ingredients from both sources.

This was a good experience and. I’'d like to try other dishes.