A British comedian who tells a crowd “I flew in from LA last week” is normally asking for a clip round the ear. For Gina Yashere, the London-born graduate of Comic Relief Does Fame Academy, going to Hollywood has been a necessity. After all, she tells us, the options for a black entertainer over here are sorely limited: “We're all waiting for Lenny Henry to die!”

What's wonderful about Yashere is the way she addresses racial issues in a way that's both direct and ironic. She generalises brightly about Americans and Brits, Nigerians and Jamaicans. But while she gets full value out of cultural archetypes - mocking white people in the front row for getting there early and black people after the interval for not sitting down soon enough - she knows that we're more than the sum of our genetic codes. “I went back to Africa to discover my roots,” she tells us, in her carefully emphatic delivery. “I discovered my roots... are in London.”

She doesn't just do race. The show is called Skinny Bitch, in honour of her going from a size 18 to a size 12, and the first half covers her weight loss, including more material about colonic irrigation than can be good for you. There's earthy - “You fart and you end up wetting some begonias behind you” - and then there's enough-already, such as calling her coffee enema “my morning Arsebucks”.

Yashere's best 70 or 80 minutes are a joy. Here, she talks for two hours, plus interval and a support act. And even though she's one of the most poised and propulsive comics I've seen, she needs tighter editing. The second half is filled with strident yet self-mocking material about her right-wing mum and her former life as a lift engineer. It's Yashere at her best. Yet, without more structure, it starts to feel a bit random - not helped by the way she keeps returning to her mic stand as if she's about to finish.

Britain's loss is America's gain, all the same. A tighter focus would be good. But Yashere has got the attitude and the delivery to ensure there will be plenty more transatlantic trips to boast about.

On tour. Next show, Royal Court, Liverpool, Thursday (www.ginayashere.com)

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