Heat enough water in a pan with salt and a few drops of oil, till it comes to a boil.
Add the hakka noodles and cook according to the package instructions.
When noodles are cooking, rinse and chop all the veggies or you can chop them before you start cooking noodles.
Drain and rinse noodles in running water, so that the noodles stop cooking.
Then add toasted sesame oil and gently mix, so that the oil gets evenly coated on them.
Set the cooked noodles aside.
Stir-frying
Heat oil in a wok or kadai or a frying pan.
On medium-low to medium heat, first add the dry red chilies and garlic.
Saute for a minute, then add the finely chopped spring onions and french beans
Increase the flame a bit and stir fry for 3 minutes. For non-stick frying pans, keep the heat to medium and for cast iron or carbon steel pans or wok, use medium-high to high heat.
Add the mushrooms, carrots, bell pepper (capsicum) and celery.
Stir fry all the veggies on a high flame till they start getting slightly browned from the edges. This will take about 5 to 6 mins after adding the carrots.
Add soy sauce and mix well.
Making hakka noodles
Add noodles and toss it well and stir fry for a minute or two on high heat.
Season with salt and pepper. Also, add rice vinegar or white vinegar. Continue to toss and cook on a high flame for a minute.
Toss the whole mixture well and add the chopped spring onion greens or garnish with spring onions while serving.
Serve hakka noodles plain or accompanied with manchurian curry or gobi manchurian or chilli mushroom.