ESI.pm

package Catalyst::View::Component::ESI;

use Moose::Role;

requires 'process';

around 'process' => sub {
  my $orig = shift;
  my $content = $orig->(@_);
  ## fix $content
  return $content;
}
1;

Something.pm

package Myapp::View::Something;

use Moose;

with 'Catalyst::View::Component::ESI';

sub process {
  return 'my template content';
}

1;