How to fit wood perfectly to rough walls like this

Saw this online and I'm itching to try something similar in my basement. You know that older space with some pretty uneven concrete walls. That clean wood against the rough wall looks awesome. But how do you get wood to fit so perfectly flush against an uneven, rough surface? #Woodworking #DIY #HomeImprovement #Carpentry #BasementRenovation #WoodworkingTips #HomeRenovation