Until recently, the innocent question "where can I go to eat good Mexican in Sydney?" was usually met with cruel laughter or the most dismissive of scoffs.

Sure, we had a few passable Mexican-inspired bars and a handful of burrito franchises that hit the spot if you are hungover enough, but actually good, authentic Mexican in Sydney? Preposterous!

A few years ago one of my loudest scoffs was rudely interrupted by a friend who exclaimed "what about that Rosa lady who sells tamales at Marrickville Market? Her food is legit."

A quick Sunday visit to Marrickville Market confirmed that this Rosa lady's tamales – steaming hot flavour-bombs of corn, meat and salsa – were indeed legit, completely devoid of the dryness that plagued every other attempt at a tamale I'd eaten in Sydney previously.

Then late last year, Rosa Cienfuegos, who moved to Sydney from Mexico City in 2009, opened Tamaleria & Mexican Deli in Dulwich Hill, a small takeaway shop that offers an always-changing selection of hot Mexican dishes, plus a nicely curated line-up of imported Mexican canned goods, dried chillies and spices.

You can eat one of Rosa's tamales while in the shop (good luck choosing between the green and red varieties; I always just get both), then hit the freezer section for some to take home.

I ask Rosa why it's so hard to find good Mexican food in Sydney. "The Mexican community in Australia is pretty small, and without an Australian public well-acquainted with real Mexican food, there is none to little demand for certain ingredients," she tells me.

"This means a lot of stuff has to be imported, meaning suppliers have to be focused on the ingredients that they can sell to a broader range of communities – or products used in the American version of Mexican food."

Plus Australians are better acquainted with Tex-Mex food than the genuine article.

"A big part of introducing Australia to good Mexican food involves educating them as to what Mexican food is in the first place," says Rosa. "People can't demand what they don't know exists."

Having eaten (and cooked) hundreds of below-average tacos in Sydney, tucking into a plate of Rosa's tacos makes me a little misty-eyed (although that may be due to my going a little overboard on her salsas).

There are always three different tacos in rotation – one vegan option and two meat, usually a sweet pork carnitas and a tender beef suadero (my favourite). All tacos are served on two small corn tortillas and can be polished off in three to four unforgettable bites.

Elsewhere on the menu you'll find other Mexico City specialties, like tlacoyos, a large torpedo of blue corn and black beans topped with cactus salad and cheese.

But there are still plenty of dishes she can't make here.

"There are a lot of fresh ingredients that have completely different flavours here or only appear in certain forms that sometimes mean you have to be clever with substitutions."

Tamaleria and Mexican Deli is open four days a week and Rosa spends the other three delivering her food all over Sydney and running the odd pop-up restaurant, not to mention the two days it takes her to make enough tamales for the week. Still, she has plans to expand. 

"Having a proper taqueria would be amazing," she says.

"I cannot wait until we have a taco bar with micheladas [chilli-spiked beer cocktails] and Mexican music, but at the moment between events, catering, and the shop, I have my hands full – but watch this space!"

The low-down

Tamaleria and Mexican Deli

Address 463 Marrickville Road, Dulwich Hill, 02 8590 1661, mexicanfoodaustralia.com.au

Bottom line Tamales $9, nachos $10

Must-order dish Taco plate $16