Tops is pretty good for soy and gluten "meats". They also carrry decent vegetables (generally better than Tesco or Big C, at any rate). The Royal Project "Doi Kham" shops (there's on in Future Park) often carry good produce as well. There are Chinese veggie places scattered around Bangkok and beyond which often also carry soy and other bean products, as well.
For restaurants, check out the
Happy Cow site.
- Reg