Add the vermicelli to a dry kadai over medium heat and roast, stirring constantly, until it turns a light golden brown and smells toasted. Set it aside on a plate.

While the vermicelli cools, finely chop the onion and coriander leaves, dice the carrot, and slit the green chilies so everything is ready before you start tempering.

Heat the oil in the same kadai over medium heat, add the mustard seeds, and let them splutter, then add the urad dal and chana dal and fry until the dals turn light golden.

Add the curry leaves, green chilies, and chopped onion to the tempering and sauté until the onion turns soft and translucent.

Add the diced carrot and green peas to the kadai and sauté for a few minutes until they turn slightly tender but still retain some bite.

Pour in the water, add the salt, and bring the mixture to a rolling boil over high heat.

Lower the heat slightly and gradually sprinkle in the roasted vermicelli, stirring continuously so it does not clump together.

Cover the kadai with a lid and let the vermicelli cook on low heat until it has absorbed all the water and turned soft.

Turn off the heat and let the upma sit covered for a couple of minutes so the residual steam finishes softening the vermicelli evenly.

Fluff the upma gently with a fork, squeeze in the lemon juice, and sprinkle the chopped coriander leaves over the top before serving.