John 10:30

I and the Father are one.

ἐγὼ καὶ ὁ πατὴρ ἕν ἐσμεν.

Greek

What we did

We kept the ASV's wording: "I and the Father are one."

Why

The rendering is exact
Each Greek word has its English counterpart: ἐγώ "I," καὶ ὁ πατήρ "and the Father," ἐσμεν "are," ἕν "one."
ἕν is neuter
It is "one (thing)," not the masculine εἷς, "one (person)." English "one" carries both, so no change in wording is needed.
The same word elsewhere in John
The neuter ἕν is used of the disciples in 17:11 ("that they may be one, even as we are") and 17:21–22 ("that they may all be one … even as we are one").
More
This version renders it "one" in each place.