[O] Multi-step ledger org-capture template

[Stefan Huchler]

I want to insert a table from a email (gnus) into org-mode but before it
gets saved it should first be converted.

I can do it manually, copy the ascii table to a org-file:
mark it then use that command:

#+begin_src emacs-lisp
(defun my-make-table ()
      "docstring"
      (interactive)
      (org-table-convert-region (region-beginning)
                                (region-end) 2))
#+end_src
   
to convert it to a org-table (2 spaces or more is a seperator)
then use the following to create ledger style transaction:

#+begin_src emacs-lisp :var mapping=food-name-mapping data=import-table
  (let* ((rev-mapping
          (mapcar (lambda (x)
                    (list (nth 1 x) (car x)))
                  mapping)))
    (mapconcat
     (lambda (line)
       (format "%s \t\t%s St {=€%s}"
               (car (assoc-default (nth 1 line) rev-mapping))
               (nth 0 line)
               (nth 4 line)))
     data "\n"))
#+end_src

it uses this mapping table:

#+NAME: food-name-mapping
| expenses:food:vegetable:bananas | Bananas 125g |
|                                 |              |

To map the names of the items of the shop to the ones I use in ledger.
First step would be to create a capture that at least imports it as
org-table something like that:

#+begin_src emacs-lisp
  ("K" "import Transaction" plain
   (file+function "~/notes/finanzen.org"
                  (lambda () ""
                    (progn (org-babel-goto-named-src-block "balance")   
                           (org-babel-goto-src-block-head)(forward-line))))
   "%(copy-region-as-kill) %(switch-buffer \"temp-ledger-import\") %(yank) 
%(mark-buffer)
  %(org-table-create-or-convert-from-region) %(buffer-string)" 
   :jump-to-captured t
   :empty-lines-after 1
   :immediate-finish nil)
#+end_src

But I would want to do both convertions before I want to capture it in
the end.  Can I do that or do I need to work with org-capture-hooks?
Any suggestions?