Gai lan is asian yes, not an herb but a brassica, common name chinese broccoli ... very easy green to grow here, long season, i'll be planting this year's first within days ... if you cut it right it comes again with double tops, then cut those right and you get four ... likes lime and high compost content as do all coles, plus needs the same seven-year rotation [don't plant in the same place for seven years, or you stand more chance of getting clubroot] ..... it has more and richer taste than commercial broccoli, flower stalks are tender down quite a ways, 15cm sometimes ..... seed is still quite expensive here, but i've only ever bought one package, just let a few plants go to seed each year, hang them to dry and pick pods, it's very quick ... my wife absolutely loves this veggie, i grab some almost every day coming out of the garden [until mid-Dec last year] and whiz it goes into food - in omelettes even, sliced finely ... here's an aussie site on it - http://www.nre.vic.gov.au/trade/asiaveg/thes-12.htm
Epazote smells like kerosene when you roll fresh leaves in the fingers -g- ... no kidding ... but the taste cooked is nothing like the smell, more subtle ... all beans in this house [and we eat a lot of them] have epazote ... word means in maya 'stinking animal', also called yerba de Santa María, makes beans less of a musical fruit [and really works] ... like cilantro it becomes a weed if you let it go to seed in the garden, worse than anything because the seeds are like dust and in the millions per plant ... mostly i just let some go wild on the side of a hill above pasture, but each year there are plants whose seed has blown near one hundred metres from there to the main garden [or got stuck to a gumboot and transported that way perhaps] .... here's a foto - http://mexico.udg.mx/cocina/glosario/g-hierbas/epazote.html
My wife has declared gai lan and perogies to be authentic comida mexicana -g- ... several other things as well, cress and a japanese mustard for instance .... hates arugula, absolutely loathes it, says of anything she doesn't like 'this tastes of arugula' -g-