Check String Starts with Vowel

Write a Python function `check_str` that determines whether a given string starts with a vowel (a, e, i, o, u) using regular expressions. The function should return `True` if the string starts with a vowel (case-insensitive) and `False` otherwise.

#### Example Usage
```python [main.nopy]
print(check_str("annie"))  # Output: True
print(check_str("dawood")) # Output: False
print(check_str("Else"))   # Output: True
```

#### Requirements
- Use regular expressions to solve the problem.
- The function should handle both uppercase and lowercase vowels.
- The function should return a boolean value.