To (re)create an EFI Partition Using gdisk in macOS

Steps:

1. Identify disk

   diskutil list  # Note target disk (e.g., /dev/disk0)

2. Launch gdisk

   sudo gdisk /dev/disk0  # Replace `disk0` with your disk

3. Delete existing EFI partition
   In gdisk:

   p             # List partitions
   d             # Delete
   [Partition #] # Enter EFI partition number (e.g., 1)

4. Create new partition
   In gdisk:

   n                          # New partition
   [Enter]                    # Default partition number
   [Enter]                    # Default first sector
   +200M                      # Partition size
   t                          # Change type
   [New partition #]          # Partition number
   EF00                       # EFI type code

5. Write changes
   In gdisk:

   w  # Write table
   y  # Confirm

6. Format partition

   sudo mkfs.fat -F32 /dev/disk0s1  # Replace with new partition ID

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Minimal Workflow Example:

diskutil list
sudo gdisk /dev/disk0
p
d
[EFI-partition-#]
n
[Enter]
[Enter]
+200M
t
[new-partition-#]
EF00
w
y
sudo mkfs.fat -F32 /dev/disk0s1