1. Prepare the rice according to package directions, but do not add any oil or butter.
2. Saute onion and red pepper in oil in large nonstick skillet until tender, about 8 minutes. Add garlic; saute for 1 minute. Stir in tomato paste. Add lemon juice, water, thyme and cayenne; cook 3 minutes.
3. Add zucchini; cook, covered, 5 minutes, adding a little water if mixture becomes too dry. Stir in tomato and shrimp; cover; simmer 10 minutes, until shrimp are cooked through. Remove from heat.
4. Heat tortillas according to package directions. Spoon about 1/3 cup of the rice and 1/2 cup of the shrimp mixture down center of each tortilla. Roll tortillas up; place, seam side down, on serving dish. Garnish tortillas with chopped tomato.