"Corn, not porn." "Roll my oats." "It's all about the soil." The messages scrawled over the recycled T-shirts worn by staff at Sydney's newest pop-up restaurant are relentlessly on-message. Greenhouse practically appeared overnight on the water's edge in The Rocks and is currently scheduled to disappear at the end of this month.

Originally a Melbourne initiative by Dutch-born florist, artist, builder and environmentalist Joost Bakker in 2008, the Greenhouse was invited to Perth, where it morphed from temporary to permanent, putting young, tousle-haired chef Matt Stone on the map (and on the telly, paired against Neil Perry on Iron Chef).

Bakker has chosen a pop-up as a vehicle for hard messages about how we should be constructing buildings, sourcing produce and materials, working with others and interacting with our planet.

Greenhouse was built using only recycled or sustainable materials. It's topped with a roof garden that supplies herbs and vegetables to the kitchen and exterior walls are vertical gardens of strawberry plants. Insulation is from hay bales sourced from local grain producers.

Inside, the flooring is made from old conveyor belting; the chairs from disused irrigation pipes. The kitchen activity is fully integrated, with nothing done by halves. There are no rubbish bins and all waste is composted. Even old oil from the deep fryers is turned into diesel to supply electricity. Oats are rolled to order, yoghurt and butter are made on the premises; and much food is cooked in a wood-fired oven.

And here's the real charm of the place: biting into nutty pizza, just-baked bread or fresh pasta, knowing it has been made from flour milled that morning. Food made from scratch, by hand, on the spot, has an energy and goodness that you can practically taste.

It might mean the freshly made herbed pasta ($22) is a little thick and chewy rather than fine and silky but it also means it is good and real, coated in a simple sauce of oven-roasted tomatoes and Ortiz anchovies that's punchy and fresh.

I like eating here; the food is simple, homely and wholemealy, with very little done for mere effect. A fresh fillet of mullet is seared and sent out with multi-hued heirloom tomatoes ($26); good, finely sliced prosciutto ($21) is strewn with figs and walnuts; and a small, doughy, wood-fired pizza is gritty with golden grain, topped with sweet pork and fennel sausage and fromage blanc ($15).

The food is served on oddly shaped boards, the beer in glasses made from cut-down and bevelled bottles, the wines in jam jars and the single dessert, a fresh, summery and hastily set watermelon jelly is served with an astringent lemon sorbet and fresh berries ($10) in yet another recycled jar.

Staff are sweetly shambolic, the menu is short and the wine list consists of two giant vats of Natural Selection white (uninspiring) and red (drinkable) from the Adelaide Hills sitting on the counter as well as a fresh, crisp rosé ($9 a glass) and classy, gutsy Sangiovese from Foster e Rocco ($10 a glass/$45 a bottle). There are draught beers from Stone and Wood and Little Creatures, Pipsqueak cider and Trade Winds gin.

You could get tired of trying to drink from jam jars without dribbling and the small, mulchable wooden cutlery is a huge encouragement to eat with your fingers. Yet it's a mesmerising place to be, with its windows open to the weather (and prime Harbour Bridge and Opera House views), its walls and ceilings scrawled with Bakker's mantras on wheat and corn, channelling the Stephen Sprouse graffiti bags for Louis Vuitton, and its magical rooftop bar. When it falls dark, it really falls dark, with only natural bees' wax candles from Queen B.

Greenhouse is an unrefined and un-cynical exercise and it's currently abuzz with Sydneysiders. You can see them wandering about with loopy smiles on their faces; thinking, working it out, getting it. They're almost creating their own energy supply by just being there.

The food may not be the real hero but the concept is. It's more creative hothouse than restaurant, pushing fresh ideas out into the atmosphere instead of noxious greenhouse gases. Whether it's temporary or not (there are moves afoot to give it a Sydney home), it makes most permanent restaurants in the world look increasingly unsustainable.

tdurack@smh.com.au