Down a Brunswick side street, groovy Stevie Wonder tunes filter from a seemingly nondescript red brick building. On the footpath outside, a sandwich board bisected in black and pink simply states "Donuts & Diner" and outdoor tables and benches are flanked by hefty potted palms. Inside it's a stripped-back cantina vibe, with bare bricks, a spinning fan, an arched window into the kitchen and shelves of fresh baked doughnuts. Welcome to Juanita Peaches.

The bricks-and-mortar operation of Raph Rashid (Taco Truck, Beatbox Kitchen), has been gradually evolving since it opened. Once just the after-hours operation of All Day Donuts (yep, he makes doughnuts too – he's the Swiss Army knife of finessed fast food), Juanita Peaches now goes all the way from morning coffee to evening treats of jalapeno margaritas and burgers and baskets of fried chicken.

The menu revels in American diner faves and Mexican classics, and while the results, served on black and white checkered paper in red plastic baskets, might look like fast food, there's nothing corner-cutting about the components. Everything is made from scratch, from the bun to the patty to the sauce.

Kick the day off with coffee and a doughnut – soft and bready, not too sweet, maybe coffee-glazed and filled with passionfruit curd or doused in strawberry frosting and a slightly salty crumble. They're available all day (hence the name) and the burgers are grilling from 11am.

Fried chicken – free-range and marinated in a brine with peppercorns, lemon, onions and more – comes in a snacky popcorn format, in a sandwich with slaw and spicy boss sauce (a chilli-laced tomato sauce), or in a box with slaw, fries and optional bread and gravy. The coating is thin, lightly spiced and crisp, the meat soft and succulent, perfect with a little dunk into the house-made barbecue sauce.

Cheeseburgers – with patties of grass-fed brisket, minced in-house at two different textures to get the perfect consistency– are super-juicy with the right amount of sweet onions and pickles. This is a multiple napkin burger, so choose your date wisely.

Burritos come filled with brown rice, cheese, slaw, salsa and black bean or fish, while the fish tacos are organic tortillas topped with a flavour-bombing mound of masa-fried fish, crunchy discs of fried jalapenos, pickled carrot and mango slaw and a thick, emerald lash of tomatillo nam jim. They're a knock-out.

There are also a couple of moles on the menu, including a pumpkin and almond one, as well as seasonal specials some Tuesdays, such as the recent General Tso's chicken, a hot and sour American-Chinese cult classic.

Drinks tip a diner hat with refillable filter coffee and Pabst Blue Ribbon beer, then swing back home with bottles of Rockies Lemonade made on site, plus Mornington Pale Ale and a couple of house wines.

Service here is as sweet as the doughnut sprinkles. Across the bottom of the A4 paper menu, it says: "The styles be low key. The vibes be high." Here, the quality be even higher. And you will be too.