My Kenwood Frothy Maker makes the spicy tomato yummy and smooth (but I don't mind froffy soup lol).
You could try mixing it into a paste with a bit of cold water, then slowly add more water in a pan over the hob - like the Roux method of making a sauce. My mum does that and she swears by it!
I hate the Spicy Tomato, its the only soup I nearly gagged with when I tasted it...although it being frothy because of my blender probably didnt help I dont like the mushroom either but the oriental chilli and the chicken and vegetable are gorgeous!
On some of the packets of spicy tomato it says that you shoudl mix it with a little cold water into a paste before adding in hot water.
I do it like this every time, then shove my stick blender in and give it a whirl.