Not the same restaurant as I think you were asking about, but I had a good dinner a couple of nights ago at another French restaurant here, Indigo. Sounds a bit similar; some seating inside, some outside. The outside tables are set in a leafy alcove - the restaurant itself is on a quiet soi, so pleasant to sit outside.
It's on Soi Convent, a few minutes walk from the Silom Complex. The menu was pretty extensive and the food wasn't bad. The tuna tartare was a tad oversalted, but the duck confit was excellent. Wine list could have been fuller, but with around 6 reds and whites each available by the glass, was perfect for me as I was driving. The bill came to THB 1,100 each (starter, main, a glass of wine and a coffee) which I thought was good vfm.