THAI-INSPIRED SHIITAKE STIR FRY

2 salad onions • 2 x 150g packs shiitake mushrooms • 1 tbsp olive oil • 1/2 x 25g pack mint, leaves only, torn • 1/2 x 25g pack coriander, chopped • Steamed jasmine rice, to serve Dressing • 1 red chilli, finely chopped • 1 stick lemongrass, finely chopped 1 clove/s garlic, finely chopped • 2 tbsp caster sugar • 1 lime, juice