In a large skillet or wok, heat 1 tbsp. oil over medium-high. Add the garlic and cook until fragrant, about 30 seconds. Add the sugar snap peas and water chestnuts; season and cook, stirring, until the peas are crisp-tender, about 2 minutes. Transfer to a medium bowl.
In the same skillet, heat the remaining 1 tbsp. oil over medium-high. Add the shrimp in a single layer. Cook, without stirring, until pink on the bottom, about 2 minutes. Turn the shrimp, add the ponzu and cook until the shrimp are cooked through, about 2 minutes. Stir in the vegetables; cook until heated through, about 2 minutes. Season and serve with the rice.