as a english speaking burger, what's the correct way to say Asuka?
While it's great that you learned hiragana anon, that's wrong. Putting ー after a syllabe means the last vowel sound is extended which isn't the case for Asuka, you're basically saying it's pronounced Aasuuka
said. Most of the time, the -u is dropped in from -u sounds in Japanese, except for t sounds where sometimes the o is dropped. That's why many people say "dess" instead of "desu," that's probably the easiest example to catch.