cheezz, try spraying a dirty sieve w/ Dawn's Power Dissolver and letting it sit a while B4
you wash it.  (Just follow the directions on the label.)  I absolutely love that stuff and use it for baked-on and burned-on gunk prior to putting  casseroles and the like into my dishwasher.  It's also a great pre-treatment for pots & pans that I hand wash.