Phase separation plays a crucial role in determining the self-assembly of biological and soft matter systems. In the former case, liquid-liquid phase separation inside a cell leads to the formation of various macromolecular aggregates. The interaction among these aggregates is soft and the particles are generally modelled by ultrasoft particles. We have studied the phase separation dynamics of size- asymmetric binary mixture of ultrasoft particles (with species A and B). When quenched to a lower temperature below critical temperature, the system undergoes a phase separation into an A-and a B-rich phase. In detailed and extensive molecular dynamics simulations (with up to 786432 particles) we have identified the critical point. When cooling the system the domains of the two components grow in a power-law manner (𝑖. 𝑒, 𝑙(𝑡)~𝑡𝛼 with an exponent α = 1/3) which is consistent with the Lifshitz-Slyozov law. In a subsequent step we have exposed the system – as it is cooled down to low temperatures - to shear and have studied the stress response of the system to the these external forces; in their presence the domains grow with exponents α = 4/3 and α = 1/3 in the shear and the gradient direction, respectively. In particular we have analysed how spatial inhomogeneities (which are characteristic for the phase separation scenario) evolve under the shear forces.