One guess, one pretty-certain and a whole bunch of Sorry-I-pass.
Tallulah seems to be a geographical name; perhaps it was only used as such by the people in whose language it originally featured, and was taken over and used as a given name by English-speaking people. Not unknown ...
Ambrosia was the food of the Greek gods - they drank nectar. Ambrosia means: immortality, and if they stopped eating it, they'd become mortal. There was a St Ambrose, much later, who would have had a different kind of immortality on his mind.
Unfortunately, the sources are silent about how it was made ... but there is a rather sinister dessert called ambrosia which is basically rice pudding with fruit salad. Avoidable. And no name for a human! Steak Diane is one thing, soggy rice pud is quite another.