My rule of thumb is a 2:1 ratio of oil to vinegar.
So in your case I would go with 2-3 Tbls of olive oil, 1-2 Tbls of cider vinegar, and then 1 tsp of honey, salt and pepper. I use kosher salt for things like this. Whisk it together and taste. If it is too sweet, a dash more of vinegar. If it is. It sweet enough add honey in 1/8 tsp increments.