2 Quick Questions - Frozen Potatoes and Tarts

[whatshallmynamebe]

I have parboiled and frozen my roast potatoes - do I need to defrost them before I cook them, or can I just chuck them in the hot fat straight out of the freezer?

Secondly, do I trim the excess pastry from my tart when it is straight out of the oven or once it has chilled? I always make such a hash of doing this.

The potatoes can go straight from freezer into very hot fat but don't know about the tart sorry.

I thought you trimmed pastry off while it's still uncooked?

I thought that too Knitter but then pastry isn't my strong point as my mince pies will testify

Trim when uncooked. Don't go too hard at it cos it will shrink a little bit so angle your knife to cut leaving a bit of a lip on the edge of the dish. Hard to explain but rather than having the knife vertical hold it at an angle away from the pastry. Also helps if you hold the tart on the flat of your hand and trim like that. Put knife down every quarter and move the untrimmed bit closer to you and repeat. Does that make any sense? I think mebbe not