Break the eggs into a bowl and add the chilli powder. Whisk well until the eggs are completely broken up. Stir in the chorizo. Heat the oil in a small frying pan for 1 minute. Tip the egg mixture into the pan. When the eggs start to set around the edges, use a fork to push the cooked parts into the centre of the pan so the uncooked egg flows into the space. Keep doing this until the eggs are no longer runny, then let the omelette cook until just set (3–5 minutes). Slide the omelette on to a plate and leave to cool.
Cut the mustard and cress from the punnet and put it in a sieve. Rinse under cold water and leave to drain.
Prepare the tortillas by heating in the microwave on full power for 10 seconds. Alternatively, warm them under a hot grill or heat in the frying pan for approximately 10 seconds (wipe out the pan with kitchen paper first, taking care as it might still be hot).
Spread one side of each of the tortillas with the pesto and lay the omelette on top. Sprinkle with the mustard and cress. Roll up tightly so the filling is completely enclosed. Cut the wraps in half, wrap in nonstick baking paper and chill in the refrigerator until ready to serve.