#!/usr/bin/perl -w
use strict;
while (<DATA>) {
  my @parts = split/ {TAB} /,$_;
  for (1..$#parts) {
    print "$parts[0]\tFeld$_\t$parts[$_]\n";
  }
}

__DATA__
ID1 {TAB} A C {TAB} A B {TAB} A T
ID2 {TAB} A H {TAB} C V {TAB} C T