Place water and farro in a medium saucepan to presoak.
Cut onion in half and very thinly slice it into quarter-moons.
Thinly slice garlic cloves.
Halve or quarter tomatoes.
Add onion, garlic, tomatoes, salt, red pepper flakes, and olive oil to the pan.
Bring the pan to a boil, then reduce to a simmer.
Cook for 30 minutes or until the farro is tender and the water is absorbed.
Transfer to a serving bowl and drizzle with olive oil.
Garnish with basil leaves and grated parmesan cheese.
Serve immediately.