In a hot frypan, saute capsicum and onion on medium-high for 5 minutes. Add garlic and saute one more minute. Stir in tomatoes and chicken stock. Remove from heat.
Place mixture in blender and blend until the desired level of chunkiness is achieved. Return to medium-low heat. Stir in tomato paste one tablespoon at a time until desired level of thickness is reached. Cook for 20 minutes, stirring occasionally.