I assume it’s Gaelic? But perhaps it’s another Celtic language?
I believe it is Irish, that is, the Irish variant of Gaelic (as opposed to Scots Gaelic or Manx). I think we have some people more versed in that language than I am who can help you with pronunciation.
I speak Irish. That’s not a possible Irish word unless the spelling has been mangled.
Brochtán means soup but I can’t figure out the second word.
I’d go with “spelling has been mangled”
An attempt to search on it resulted in a LOT of recipes but not much else. Oh, apparently an alternate term is brochtán roy which looks like an Irish/French-by-way-of-English mash-up to me. The first word might be soup but the second is neither “oatmeal” nor “leek”.
I can’t find that word in anything other than recipes or articles talking about the soup.
However, Brothcháin is Middle Irish, and appears in Aislinge Meic Con Glinne (the Vision of Mac Conglinne).
Translation would appear to be “pottage”, if I’m reading correctly. This is the relevant Middle Irish, expanded to single lines for clarity, followed by the English:
Conid ind sin ruc-som Manchín iar ngenelach bíd co h-Ádam:
`Bennach dún, a chlérig,a chlí chloth co comgne’;
mac Midbuilce mela,
meic Bela,
meic Bloince,
meic Buaidrén,
meic Brothcháin,
meic Borr-Thoraid brec-báin,
meic Borr-Chrothi bláthi,
meic Bláithche,
meic Brechtáin,
meic Beóiri, buaid mbainde,
meic Brocóti binde,
meic Cainninde caimme,
meic Shaille,
meic Imme,
meic Indrechtáin lán-méith,
meic Lemnachtai immglain,
And this is an English translation:
Then it was that he traced Manchin back to Adam, according to the pedigree of food, saying:
Bless us, O cleric, famous pillar of learning,
Son of honey-bag,
son of juice,
son of lard,
Son of stirabout,
son of pottage,
son of fair speckled fruit-clusters,
Son of smooth clustering cream,
son of buttermilk,
son of curds,
Son of beer (glory of liquors!),
son of pleasant bragget,
Son of twisted leek,
son of bacon,
son of butter,
Son of full-fat sausage,
son of pure new milk,
Note that the other bolded bit, “twisted leek”, doesn’t appear to be anything like “foltchep”
foltchíp = leek
according to
Translation is given as
I recognise that man from his description,’ said Medb.
Royal champion,
victorious ruler,
vessel of Bodb,
destructive fury,
avenging flame,
countenance of a hero,
bearing of a champion,
heart of a dragon,
sharp-wounding valorous hero (?) who will cut us to pieces,
Loegaire, the fearsome Luchdonn with the red hand,
as the swinging stroke with sharp edge
shaves the leek to the ground.
Foclóir Gaeilge–Béarla (Ó Dónaill): foltchíb translates foltchíb as “leek”, while
eDIL - Irish Language Dictionary mentions (1) chives and (2) hair of the head, beard in the sharp shaving metaphor quoted above
Yes, looks like leek could be foltchíb as well as cainneann. I’m assuming that -chib is the modern spelling and -chip or -chep is older. But I know less than nothing about Irish orthography.
I, too, know pretty much the same about Irish orthographic history; maybe I heard the word “Ogham” once, and about some kind of controversial huge modern spelling reform, so nothing to add to that at present, but I was wondering whether— looking at a Scottish lexicon this time, where “folt-chìob” is translated as “leek/chive/onion flower”— whether the chep/cheip/chip/chib/chiob element is analogous to “chive” (cf. Latin “cepa”), making foltchip parse as something like “chive hair”?
I believe there are some great new potential screen names in the list in this post. Or possibly insults.
Also, Dopers know abso-fucking-lutely everything. Or they will find out. Carry on.
Medieval food is my thing, so I was aware of the Vision and where to start looking before this.
“Son of pottage” - them’s fightin’ words. 
Great detective work by fellow-Dopers tracking down these words!
To summarise:
Modern Irish brochán (variant brachán) means porridge or gruel, from Middle Irish brothchán meaning soup or porridge.
Modern Irish foltchíb means leek, combining the word “folt” meaning hair of the head and “cíb” or “cíob” meaning sedge.
I have never come across either of these words but they are in the dictionary.
The OP asked about pronunciation, so here goes. Modern Irish spelling and pronunciation because otherwise I haven’t a clue.
brochán: bruckawn. 1st syllable to rhyme with English word “tuck” but instead of a k sound at the end, you have the throaty “ch” sound that is written as /x/ in IPA. Second syllable like the “awn-” in the word “awning”.
folt-chíb; fult-keeb. 1st syllable rhymes with the English word “cult”. Second syllable is like “keeb” but again, with that throaty /x/ sound instead of the k sound.
Great, thanks!!