Sift flour and salt into large bowl; stir in yeast. Add the water and 1 tablespoon of the olive oil; stir until mixture becomes a sticky dough. Turn dough onto floured surface; knead until smooth and dough loses its stickiness. Place dough in oiled large bowl, cover; stand in warm place about 1 hour or until doubled in size.

Meanwhile, peel and finely chop onion; peel and coarsely grate carrot. Peel and crush garlic.

Heat remaining oil in large frying pan; cook onion and carrot, stirring, until softened. Add beef; cook, stirring, until browned. Stir in garlic, season to taste; cool. Stir in mayonnaise and dill.

To make piroshki: line tray with baking paper. Punch down dough. With oiled hands, pinch off about 60g (2 ounces) of dough (about the size of a lime); flatten in palm of hand into a 10cm (4-inch) round. Place a heaped tablespoon of beef mixture in the centre of the dough; fold edges over to enclose filling, press to seal. Place, seam-side down, on tray. Repeat with remaining dough and filling to make 12 piroshki.

Heat vegetable oil in large frying pan; shallow-fry piroshky, in batches, about 2 minutes each side or until browned lightly and crisp. Drain on absorbent paper. Serve immediately.