Start by chopping the veggies into chunks, like shown.
Transfer to a bowl and season as per your preference.
Squeeze some lemon juice into it and add the cilantro.
Toss well and let it chill for 10 minutes.
Notes
This Indian salad is best served chilled. Don't skip letting it rest in the refrigerator for 10 minutes before you serve. This helps the veggies start to soften just a bit, and will give you that perfect balance of flavor and texture.
If you're worried about the red onion being too pungent, peel and soak it in cold water for a few minutes before chopping it.
To add a bit of texture, you can also add some crunchy masala peanuts or toasted sesame seeds into the salad. This isn't the classic, but it adds a fun textural element to the salad.
This salad is best made and served fresh. The veggies that go into making it tend to release water after they're cut, and prepping the salad ahead of time will only make it soggy and watery.
Chop up the veggies into the size you prefer. I love chopping them in these little chunks, but you can cut them more finely or even slice them if you want to.