Michael Donkor, 39, was born in London to Ghanaian parents. His first novel, Hold (2018), about three teenage girls, was listed for the Dylan Thomas prize and the Desmond Elliott prize. His second, Grow Where They Fall, follows Kwame, a secondary school teacher, which was Donkor’s own job until his recent move to Lisbon, where he now works as a bookseller.

Where did this book begin?
I’d had some experiences – some challenging, some comic – of being in incredibly white environments, and I wondered whether a novel might be a place to think through those experiences. It wasn’t that after publishing Hold I just woke up and was like, OK, now I’m going to write the book about me. Nothing Kwame goes through specifically happened to me. He’s more someone I wished I’d had around in those racially vexed moments when I felt uncertain about what was going on in a room. I thought of him as the person I wanted to see when the headteacher was in the staff room saying: “Oh, we need to do more stuff about Black history,” and I could sense people looking at me. I’d desperately wanted someone to lock eyes with and be like, “This is weird, isn’t it?”

Did your work as a teacher give you a fund of material for fiction?
Making Kwame a teacher felt a slight risk because I worried I wouldn’t know how to use my knowledge in a way that wasn’t just me writing polemic: “I’ve been teaching for over a decade at three different places, let me tell you what I know…” I could write another two whole novels about that! I was keen to show the ordinariness of the exchanges between Kwame and his students. In the political conversation about education, there’s little attention paid to the real human work – what it costs for a person to wake up at 6am and finish at 8pm after marking and to have more than 100 conversations every single day.

What led you to the book’s matter-of-fact candour about gay sex?
Sometimes in queer novels there’s a titillating quality; I wanted the sex to feel sexy but I didn’t want people rubbing their thighs. Did I sense my teacherly responsibilities or the attitudes I suppose my students might have reading a novel where Mr Donkor’s written about willies and cum and stuff? I don’t know how I managed this, but honestly, when I sit down to write, I forget everyone else: it’s just me, the characters and the 500 words I’ve set myself to tackle.

In writing a big social novel full of dialogue, did you feel like you were working against the trend for more interior, fragmentary novels?
I really admire Deborah Levy and Rachel Cusk but much as I enjoy flintier stuff, I also enjoy a good yarn: the sort of novel where you think, I’m going to be held in a close embrace for 400 pages in a world that is very fully described. I really like novels where there’s a sense of the narrator being conversational. That doesn’t mean that they’re necessarily in slang or dialect – it’s about creating a voice that is inviting and feels like someone is speaking the novel to you. When I’m writing I read my work aloud a lot; I want it to sound as if you’re mid-conversation rather than something distant and arch.

Name a novel you’ve enjoyed recently.
Something I’ve been recommending in the bookshop where I work is Constance Debré’s Love Me Tender. I love its gutsiness: how she can be the sort of mother she wants to be, and how she can mother herself as she goes through this transitional moment of fully embracing her queerness, were questions I found really compelling. And the sex was fun and direct: “No need to be nervous but, yes, I’m going to talk about my dildo now.” I also loved Vladimir [by Julia May Jonas], for its wildly unpredictable over-the-topness and astute understanding of the negotiations involved in long-term relationships.

How come you left London for Lisbon?
It was a post-pandemic, let’s-do-something-adventurous decision. We came in July 2022. My husband and I got married here six years ago and we know the city quite well. People ask me: “Is it really creatively inspiring? Are its colours making you think in new ways?” I’m like, I dunno; so far I only know what it’s like to edit a novel here! Among the English-language community there’s definitely a developing creative writing scene. There’s this huge influx of British and American people and lots of them have creative ambitions. People from San Francisco and Stoke Newington tell me they’re in the middle of writing their Lisbon novel. So I would not be surprised if there’s a new kind of genre in the next five years, the Lisbon expat novel – it’s coming, I think.

Tell us about a novel you remember reading as a child.
I was about 11 the first time I read a novel about Ghana: Comfort Herself, by Geraldine Kaye, who was actually a white woman. It’s about a British-Ghanaian girl in Ghana for the first time. She doesn’t like the food, she’s confused about the values of the place and thinks her grandmother’s really harsh; then her relationship with this place that she’s from, but didn’t feel like she was from, develops and softens. I experienced the thrill of reading something and thinking, “I’ve been there, it is like that!” As I’ve gotten older, that magic of representation has a slightly different quality. The question of representation feels more nuanced for me now – it needs to be more than: “Let’s write a documentary-type novel about what it means to be Black.” I want more specificity: to say something new or different to make us reconsider what we think we know about Black experience.

• Grow Where They Fall will be published on 7 March by Fig Tree (£16.99). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply