use Regexp::Common qw/delimited/;

my $str = q{ x "foo \"bar\"" y };
$str =~ /($RE{delimited}{-delim=>'"'})/;
print $1, "\n";

print $RE{delimited}{-delim=>'"'}, "\n";

__END__

"foo \"bar\""
(?:(?|(?:\")(?:[^\\\"]*(?:\\.[^\\\"]*)*)(?:\")))