Thanks for your quick reply.
I adapted the code to fit my needs:

echo ‘<div class=”tab first_tab active_tab widget_tab_comments”><span>’.__(‘Comments’, ‘avia_framework’).'</span></div>’;
echo “<div class=’tab_content active_tab_content’>”;
avia_get_comment_list( array(‘number’ => $posts, ‘status’ => ‘approve’, ‘order’ => ‘DESC’) );
echo “</div>”;

echo ‘<div class=”tab widget_tab_recent”><span>’.__(‘Recent’, ‘avia_framework’).'</span></div>’;
echo “<div class=’tab_content’>”;
avia_get_post_list(‘showposts=’. $posts .’&orderby=post_date&order=desc’);
echo “</div>”;

echo ‘<div class=”tab widget_tab_popular”><span>’.__(‘Popular’, ‘avia_framework’).'</span></div>’;
echo “<div class=’tab_content’>”;
avia_get_post_list(‘cat=&orderby=comment_count&posts_per_page=’.$posts);
echo “</div>”;