We wanted a way to create a minimal config with as little noise as possible.  With the current approach, we disable all config files like so:

node.default['asterisk']['configure'].each do |config, enabled|
  node.set['asterisk']['configure'][config] = false
end

However, I'm not married to that approach at all.  If the core cookbook only installs minimal, sensible config (no jabber, gtalk, etc.), then this might not be necessary.