Ruud, I know you're patiently awaiting my help. ;~}
Well, I agree with Ross & Christian,
But it seems odd:
Ochre
Poker (fire)
Smoke(r)
Toke
Focus
Choke (car engine burn fuel)
= "okV" ~ cf olaah @ Hbr : burnt offering; olah @ Bsq : forge
*ker- (3)
Proto-Indo-European root meaning "heat, fire."
It forms all or part of: carbon; carboniferous; carbuncle; cremate; cremation; hearth.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit kudayati "singes;" Latin carbo "a coal, glowing coal; charcoal," cremare "to burn;" Lithuanian kuriu, kurti "to heat," karštas "hot," krosnis "oven;" Old Church Slavonic kurjo "to smoke," krada "fireplace, hearth;" Russian ceren "brazier;" Old High German harsta "roasting;" Gothic hauri "coal;" Old Norse hyrr "fire;" Old English heorð "hearth."
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[The only (fire)place where it is safe to strike a spark/forge?]
PIE *kau- "to hew, strike," a root more widely developed in Slavic (source also of Old Church Slavonic kovo, Lithuanian kauti "to strike, beat, fight;" Polish kuć "to forge," Russian kovat' "to strike, hammer, forge;" Latin cudere "to strike, beat;" Middle Irish cuad "beat, fight").
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smoke (n.1)
late Old English smoca (rare) "fumes and volatile material given off by burning substances," related to smeocan "give off smoke," from Proto-Germanic *smuk- (source also of Middle Dutch smooc, Dutch smook, Middle High German smouch, German Schmauch), from PIE root *smeug- "to smoke; smoke" (source also of Armenian mux "smoke," Greek smykhein "to burn with smoldering flame," Old Irish much, Welsh mwg "smoke"
[I would even venture a possible link to oracle / ora-, aurah, aurat @Arb, though others will think it is nonsense.]
oracle (n.)
late 14c., "a message from a god expressed by divine inspiration through a priest or priestess," in answer to a human inquiry, usually respecting some future event, from Old French oracle "temple, house of prayer; oracle" (12c.) and directly from Latin oraculum, oraclum "divine announcement, oracle; place where oracles are given," from ōrare "to pray to, plead to, beseech" (see orator), with material instrumental suffix -culo.
Cheers!
DD