Heat oil in a skillet or frying pan over medium heat.
Add mustard seeds and let them splutter.
Add cumin seeds, curry leaves, and chopped green chilies. Sauté for a minute.
Add chopped onions and sauté until they turn translucent.
Add grated ginger and cook for another minute.
Add chopped carrots, green peas, and bell peppers (if using). Cook for 2-3 minutes until the vegetables are slightly tender.
In the meantime, dry roast the semolina (rava) in a separate pan for a few minutes until it turns aromatic and lightly golden. Keep stirring to prevent burning.
Add the roasted semolina (rava) to the skillet with the sautéed vegetables. Mix well to combine.
In a separate saucepan, bring water to a boil.
Slowly add the boiling water to the semolina and vegetable mixture, stirring continuously to avoid lumps.
Reduce the heat to low, cover the pan, and let it cook for 5-7 minutes or until the semolina absorbs the water and becomes soft and fluffy.
Add salt and mix well. Adjust seasoning according to your taste.
Remove from heat and let it sit covered for a few minutes.
Garnish with fresh coriander leaves.
Serve the vegan Upma hot with lemon wedges (optional).