The first time I recall hearing this word was in a recording of an Irishman (middle east coast, I think) that I was listening to for accent acquisition purposes. He talked about dulse, which the fisherman liked to eat because “it gave them a good thirst for their porter.”
What I recall most particularly about his pronunciation was the intrusive schwa. Irish accents, due to a feature of Irish phonotactics, militate against adjacency of /l/ and any of several other consonants. You will hear “fillum” for film, for instance. And so dulse in that accent sounds like Dulles, as in John Foster, as in the Saarinen-designed international airport near Washington DC.
But there’s a good reason for that: the word it comes from in Old Irish is duilesc (in Scots Gaelic, duileasg). There’s an actual e written there. In the English transcription, it was dropped – because they’ll say it anyway. (The e on the end is likely there to keep the s as /s/ and not /z/.) All the non-Irish Anglos, however, seeing the spelling, make it rhyme with pulse and Hulce (as in Tom, the actor). Which actually results in a different sound for the phoneme /l/: back of the tongue higher, tip tense and touching less (if at all). Readier to swallow.
What is dulse? A vegetable, but not a pulse. It’s a kind of seaweed, and yes, it does give you a good thirst for porter or whatever else may be to hand that is wet and copious and dulls the desire. I will say it’s not the dullest thing I’ve ever tasted, nor is it dolce. A bit more like salty licorice painted onto a dishwashing glove. Not the sort of delicacy one fights duels over. In fact, it’s not really a delicacy at all – it’s available in quantity, cheap, and is not actually disgusting.
The phonetically inclined may notice that dulse in the Irish pronunciation, /dʌləs/, is very nearly a rearrangement (anaphone?) of /sæləd/. (A closer anaphone of salad would be dull-ass.) Well enough: you could make a salad of dulse. Mind you, you would probably find yourself wishing you had just eaten it by hand out of a bag. It’s not the sort of seaweed you get on your sushi (which, it occurs to me, I ate at Dulles when we were waiting for our flight home). It’s about as thick as the schwa between /l/ and /s/ in that Irish pronunciation. I mean, it wouldn’t be a dull-ass salad. But it schwa could be intrusive. Better to keep one hand free for your porter.