The TCS is kicking in because the car wants to rotate, which is the rear axle trying to overtake the front. Simple answer is to slow down and realise that you're going too fast for the conditions, be that road, weather, car, or talent.
The better answer is to not run mixed tyres at the same time. Have a read and decide for yourself. You're experiencing the randomness that mixed tyres can bring into the equation when pushing on, especially in the winter.