Toast cumin and coriander seeds in a small, dry skillet over medium-high heat, shaking the pan, until fragrant, 30 to 40 seconds . Let cool and crush with the bottom of a heavy pan.
Heat oil in a large heavy skillet over medium-high heat. Add shrimp and crushed red pepper and cook, stirring occasionally, until the shrimp turn bright pink, 2 to 3 minutes. Transfer to a plate with a slotted spoon. Season with salt and pepper and set aside.dd shallot, garlic, ginger, curry powder and the crushed cumin and coriander seeds to the pan. Cook, stirring, until the shallot is lightly browned, about 1 minute. Stir in tomatoes, peppers and zucchini. Cook the mixture over medium heat, stirring often, until the sauce is slightly thickened, 8 to 10 minutes. Add the reserved shrimp, cilantro (or parsley) and lemon juice to the pan and heat through.