Peel and wash the carrot and slice or cut into thin strips. Clean, wash and slice or cut radishes into wafer-thin strips. Cut, seed, wash and finely chop the chilli. Mix carrot, radishes, half chilli, vinegar and 1 teaspoon sugar. Wash the salad, dab dry. Wash the herbs and remove the leaves.
For the omelette, clean, wash and cut spring onions into rings. Whisk eggs, fish sauce, spring onions and the rest of the chilli. Season with salt and pepper. Heat oil in a pan. Fry the eggs for 2-3 minutes on each side to make an omelette.
Cut the baguette in half lengthwise and crosswise. Spread with butter, then cover the lower halves with salad, cold cuts, marinated vegetables, 1⁄2 omelette and herbs. Place the upper halves on top. Serve with chilli sauce.