So I had never really had a tropical style foreign extra stout so I picked up a 6 pack of Lion Stout (Sri Lanka) yesterday. It's quite good. Low on the roast and a touch fruity, just like the style guidelines say.
Hm, I've only seen bottles.
I'm thinking take a normal stout, dial down the roast and hops, up the caramel a bit, and a slightly fruity yeast. Nothing clean, but no phenolics at all. Maybe a semi-clean yeast fermented just a touch warm.
Man, this is the single worst part of the BJCP classifications, since Foreign Export and Tropical are both lumped into "Foreign Export Stout". Tropical Stouts are basically sweet stouts with a little more gravity. Probably not necessary to add unfermentables like lactose since you will be bumping the gravity up a bit from a typical sweet stout.
Here is what Jamil suggests in Brewing Classic Styles:
boil 60 min
14 lbs British Pale malt (or 10 lbs pale LME if extract)
3/4 lb roasted barley
10oz crystal 40
10oz crystal 80
1/2 lb chocolate malt
2.5 oz EKG 5%AA @60 min
WLP 013 or Wyeast 1028 (using an English yeast is important because of the slightly lower attenuation. For an export version, sub an American ale yeast like 1056. )
Ferment around 67F, raising to 70 at the end of fermentation for a diacetyl rest.