Disclaimer: I suck at cooking.

I am trying to make a curry recipe that basically goes like this:

Brown beef with onions
Add to water
Add other veggies
boil
add curry block
simmer for a while

The problem is this: Even though I don't try to over-cook the beef
during the browning part, when I start boiling it, it tends to shrink
and get hard. Is there a way I can prevent this, without resorting to
simmering for a really long time?