Sql to get tags in linking table

The quick, *****¹ish solution would be to wrap your entire query in an outer query, and only return records containing the appropriate tag using WHERE tags LIKE '%....%. This is fragile, because there's always the chance that you'll have one tag (e.g. "berry") that is container within another (e.g. "strawberry"). There are ways around this, but they're not pretty and not very SQLish.

A slightly more correct (and equally untested!) solution would be to add the original query as a subquery in your WHERE clause:

WHERE EXISTS
(
  SELECT
    1
  FROM
    tbl_talks
    LEFT JOIN tbl_linking_talk_tag
      ON tbl_talks.talk_id = tbl_linking_talk_tag.talk_id
    LEFT JOIN tbl_tag
      ON tbl_linking_talk_tag.tag_id = tbl_tag.tag_id
  WHERE
    tbl_tag.tag_id IN (the, tag_ids, you, want)
)

There might be a simpler built-in way of doing this in MySQL, but I don't know it.