Here's a recipe that worked out pretty good (by my standards).
Slice carrots and asparagus up into round 1 cm thick discs. Fry them quickly in a pan of oil for a minute or 2, with soy sauce. Prepare portabello mushroom (with stalk removed). Spread a layer of coriander on the underside of the cap (where the gills are). Then top it up with small raw shrimps. Then add the vegetables onto the mushroom. Add a touch more coriander to the top and bake the shroom for 20 mins at 400 F. 2 large sized shrooms is sufficient for 1 serving. (ok, maybe not for people with small appetites).

Going off to see the Redwoods next weekend!! Will update on that.