Convert Array into Ul-Li

Perhaps this is recursion you seek.

function olLiTree( $tree ) {
    echo '<ul>';
    foreach ( $tree as $item ) {
        echo "<li id=\"$item[id]\" parent_id=\"$item[parent_id]\" > $item[name] </li>";
        if ( isset( $item['children'] ) ) {
            olLiTree( $item['children'] );
        }
    }
    echo '</ul>';
}