The phrase "to assemble the bowls" means to put together or gather the necessary ingredients and components needed to make a bowl-based meal or dish. Full definition
To assemble bowl add lettuce and top with butternut squash, chopped chicken and avocado pieces. (littlebitsof.com)
Once the meatballs, quinoa and veggies are cooked, you can begin assembling the bowls. (crumbtopbaking.com)
Simply bring all the ingredients with you including the cooked mushrooms then heat the quinoa and assemble the bowl right where you're at! (pathoflifebrand.com)