I remember reading a shoujo about this girl who lives with her dad and her dad is getting remarried?? And so she ends up having this girl as a step sister.

The heroine was very uhh straight forward and cold.
The sister seems kind of timid and she had black hair and wore glasses.

The heroine kind of gets harassed by a couple of guys that also lived in the apartment complex, they are the step-sister's childhood friends and they thought the heroine was kind of bitchy and wanted to protect their friend or whatever.

I also remember there was a scene where they were having BBQ and she was raising some vegetables herself on their little patio. @_@
Help.

That's probably Yuugure Light ^^

Yes, that's it. Thank you~