diff --git a/README.md b/README.md
index 2d2af20..ad49ebe 100644
--- a/README.md
+++ b/README.md
@@ -48,6 +48,26 @@ Remove old generations from EFI:
 sudo /run/current-system/bin/switch-to-configuration boot
 ```
 
+## Evaluate configuration.nix to JSON
+
+TODO: https://nixos.org/manual/nix/stable/command-ref/new-cli/nix3-show-config.html
+
+* https://discourse.nixos.org/t/can-i-run-nix-instantiate-eval-strict-on-my-configuration-nix/7105/4?u=langfingaz
+
+This evaluates `configuration.nix` (single module):
+
+```shell
+NIXPKGS_ALLOW_UNFREE=1 nix-instantiate --strict --json --eval -E '
+import ./yodaTab/configuration.nix  {
+  config = {};
+  pkgs = import <nixpkgs> {};
+  lib = import <nixpkgs/lib>;
+}
+' > evaluated-config.json
+```
+
+Then open [evaluated-config.json](evaluated-config.json).
+
 ## Install Home Manager with niv
 
 niv: