mngmt ~$ lsblk -po NAME,SIZE,RM,RO,FSTYPE,TYPE,LABEL,MOUNTPOINT
NAME           SIZE RM RO FSTYPE      TYPE LABEL  MOUNTPOINT
/dev/sda     167,7G  0  0             disk
├─/dev/sda1    243M  0  0 ext2        part boot
├─/dev/sda2      1K  0  0             part
└─/dev/sda5  167,5G  0  0 LVM2_member part
/dev/sdb       3,7G  1  0             disk
├─/dev/sdb1   43,9M  1  0 vfat        part boot
└─/dev/sdb2    1,7G  1  0 ext4        part rootfs

mngmt ~$ sudo -Es
mngmt ~# mkdir /mnt/sdb1
mngmt ~# mkdir /mnt/sdb2
mngmt ~# mount /dev/sdb1 /mnt/sdb1
mngmt ~# mount /dev/sdb2 /mnt/sdb2
mngmt ~# rm -r /mnt/sdb1/*
mngmt ~# rm -r /mnt/sdb2/*

mngmt ~# tar -xf boot-partition.tar.gz -C /mnt/sdb1
mngmt ~# tar -xf root-partition.tar.gz -C /mnt/sdb2

mngmt ~# sed -i 's/ root=PARTUUID=[a-z0-9]*-0/ root=/dev/mmcblk0p/' /mnt/sdb1/cmdline.txt
mngmt ~# sed -i 's/^PARTUUID=[a-z0-9]*-0//dev/mmcblk0p/' /mnt/sdb2/etc/fstab
mngmt ~# umount /mnt/sdb1
mngmt ~# umount /mnt/sdb2
mngmt ~# exit
mngmt ~$