Eggs prepared - that is always lacking in English dish (5)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

RO e S (masses of fish eggs) + I e (id est; that is) excluding all occurrences of (always lacking) the letter E (English) – I think ‘prepared’ is just a link word to ensure that ‘is’ is the appropriate verb in the clue